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Sample records for afterglow emission intrinsically

  1. The early high-energy afterglow emission from short GRBs

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We calculate the high energy afterglow emission from short Gamma-Ray Bursts(SGRBs) in the external shock model.There are two possible components contributing to the high energy afterglow:electron synchrotron emission and synchrotron self-Compton(SSC) emission.We find that for typical parameter values of SGRBs,the early high-energy afterglow emission in 10 MeV-10 GeV is dominated by synchrotron emission.For a burst occurring at redshift z = 0.1,the high-energy emission can be detectable by Fermi LAT if the blast wave has energy E ≥ 1051 ergs and the fraction of electron energy εe≥ 0.1.This provides a possible explanation for the high energy tail of SGRB 081024B.

  2. The Interpretation of the Multi-wavelength Afterglow Emission of Short GRB 140903A

    Science.gov (United States)

    Zhang, Shuai; Jin, Zhi-Ping; Wang, Yuan-Zhu; Wei, Da-Ming

    2017-01-01

    GRB 140903A, a short duration γ-ray burst (SGRB) detected by Swift, is characterized by its long-lasting radio emission among SGRBs. In addition to the ∼ {10}6 s radio afterglow emission, the afterglow of GRB 140903A displays a plateau from 103 s to 7× {10}3 {{s}} in the X-rays. In this work, we attribute the X-ray plateau to the energy injection into the decelerating blast wave and then model the later radio/optical/X-ray afterglow emission within the standard fireball afterglow model. The afterglow emission has been well reproduced with reasonable physical parameters, including a jet half-opening angle of ∼0.05.

  3. Gamma Ray Burst reverse shock emission in early radio afterglows

    CERN Document Server

    Resmi, Lekshmi

    2016-01-01

    Reverse shock (RS) emission from Gamma Ray Bursts is an important tool in investigating the nature of the ejecta from the central engine. If the ejecta magnetization is not high enough to suppress the RS, a strong RS emission component, usually peaking in the optical/IR band early on, would give important contribution to early afterglow light curves. In the radio band, synchrotron self-absorption may suppress early RS emission, and also delay the RS peak time. In this paper, we calculate the self-absorbed RS emission in the radio band for different dynamical conditions. In particular, we stress that the RS radio emission is subject to self-absorption in both reverse and forward shocks. We calculate the ratio between the reverse to forward shock flux at the RS peak time for different frequencies, which is a measure of the detectability of the RS emission component. We then constrain the range of physical parameters for a detectable RS, in particular the role of magnetization. We notice that unlike optical RS e...

  4. Evidence for intrinsic absorption in the Swift X-ray afterglows

    CERN Document Server

    Campana, S; Covino, S; Lazzati, D; De Luca, A; Chincarini, G; Moretti, A; Tagliaferri, G; Cusumano, G; Giommi, P; Mangano, V; Perri, M; La Parola, V; Capalbi, M; Mineo, T; Antonelli, L A; Burrows, D N; Hill, J E; Racusin, J L; Kennea, J A; Morris, D C; Pagani, C; Nousek, J A; Osborne, J P; Goad, M R; Page, K L; Beardmore, A P; Godet, O; O'Brien, P T; Wells, A A; Angelini, L; Gehrels, N

    2006-01-01

    Gamma-ray burst (GRB) progenitors are observationally linked to the death of massive stars. X-ray studies of the GRB afterglows can deepen our knowledge of the ionization status and metal abundances of the matter in the GRB environment. Moreover, the presence of local matter can be inferred through its fingerprints in the X-ray spectrum, i.e. the presence of absorption higher than the Galactic value. A few studies based on BeppoSAX and XMM-Newton found evidence of higher than Galactic values for the column density in a number of GRB afterglows. Here we report on a systematic analysis of 17 GRBs observed by Swift up to April 15, 2005. We observed a large number of GRBs with an excess of column density. Our sample, together with previous determinations of the intrinsic column densities for GRBs with known redshift, provides evidence for a distribution of absorption consistent with that predicted for randomly occurring GRB within molecular clouds.

  5. GRB off-axis afterglows and the emission from the accompanying supernovae

    CERN Document Server

    Kathirgamaraju, Adithan; Giannios, Dimitrios

    2016-01-01

    Gamma-Ray Burst (GRB) afterglows are likely produced in the shock that is driven as the GRB jet interacts with the external medium. Long duration GRBs are also associated with powerful supernovae (SN). We consider the optical and radio afterglows of long GRBs for both blasts viewed along the jet axis ("on-axis" afterglows) and misaligned observes ("off-axis" afterglows). Comparing the optical emission from the afterglow with that of the accompanying SN, using SN 1998bw as an archetype, we find that only a few percent of afterglows viewed off-axis are brighter than the SN. For observable optical off-axis afterglows the viewing angle is at most twice the half-opening angle of the GRB jet. Radio off-axis afterglows should be detected with upcoming radio surveys within a few hundred Mpc. We propose that these surveys will act as "radio triggers," and that dedicated radio facilities should follow-up these sources. Follow-ups can unveil the presence of the radio supernova remnant, if present. In addition, they can ...

  6. GRB off-axis afterglows and the emission from the accompanying supernovae

    Science.gov (United States)

    Kathirgamaraju, Adithan; Barniol Duran, Rodolfo; Giannios, Dimitrios

    2016-09-01

    Gamma-ray burst (GRB) afterglows are likely produced in the shock that is driven as the GRB jet interacts with the external medium. Long-duration GRBs are also associated with powerful supernovae (SNe). We consider the optical and radio afterglows of long GRBs for both blasts viewed along the jet axis (`on-axis' afterglows) and misaligned observes (`off-axis' afterglows). Comparing the optical emission from the afterglow with that of the accompanying SN, using SN 1998bw as an archetype, we find that only a few per cent of afterglows viewed off-axis are brighter than the SN. For observable optical off-axis afterglows, the viewing angle is at most twice the half-opening angle of the GRB jet. Radio off-axis afterglows should be detected with upcoming radio surveys within a few hundred Mpc. We propose that these surveys will act as `radio triggers', and that dedicated radio facilities should follow-up these sources. Follow-ups can unveil the presence of the radio SN remnant, if present. In addition, they can probe the presence of a mildly relativistic component, either associated with the GRB jet or the SN ejecta, expected in these sources.

  7. Can the forward-shock model account for the multiwavelength emission of GRB afterglow 090510 ?

    CERN Document Server

    Neamus, Ano

    2010-01-01

    GRB 090510 is the first burst whose afterglow emission above 100 MeV was measured by Fermi over two decades in time. Owing to its power-law temporal decay and power-law spectrum, it seems likely that the high-energy emission is from the forward-shock energizing the ambient medium (the standard blast-wave model for GRB afterglows), the GeV flux and its decay rate being consistent with that model's expectations. However, the synchrotron emission from a collimated outflow (the standard jet model) has difficulties in accounting for the lower-energy afterglow emission, where a simultaneous break occurs in the optical and X-ray light-curves at 2 ks, but with the optical flux decay (before and after the break) being much slower than in the X-rays (at same time). The measured X-ray and GeV fluxes are incompatible with the higher-energy afterglow emission being from same spectral component as the lower-energy afterglow emission, which suggests a synchrotron self-Compton model for this afterglow. Cessation of energy in...

  8. A Comprehensive Study of Gamma-Ray Burst Optical Emission: III. Brightness Distributions and Luminosity Functions of Optical Afterglows

    CERN Document Server

    Wang, Xiang-Gao; Li, Liang; Lu, Rui-Jing; Wei, Jian-Yan; Zhang, Bing

    2013-01-01

    We continue our systematic statistical study on optical afterglow data of gamma-ray bursts (GRBs). We present the apparent magnitude distributions of early optical afterglows at different epochs (t= 10^2 s, t = 10^3 s, and 1 hour) for the optical lightcurves of a sample of 93 GRBs (the global sample), and for sub-samples with an afterglow onset bump or a shallow decay segment. For the onset sample and shallow decay sample we also present the brightness distribution at the peak time t_{p} and break time t_{b}, respectively. All the distributions can be fit with Gaussian functions. We further perform Monte Carlo simulations to infer the luminosity function of GRB optical emission at the rest-frame time 10^3 seconds, t_{p}, and t_{b}, respectively. Our results show that a single power-law luminosity function is adequate to model the data, with indices -1.40+/-0.10, -1.06+/- 0.16, and -1.54\\+/- 0.22, respectively. Based on the derived rest-frame 10^3 s luminosity function, we generate the intrinsic distribution o...

  9. Polarization of prompt and afterglow emission of Gamma-Ray Bursts

    CERN Document Server

    Covino, Stefano

    2016-01-01

    Gamma-ray bursts and their afterglows are thought to be produced by an ultra-relativistic jet. One of the most important open questions is the outflow composition: the energy may be carried out from the central source either as kinetic energy (of baryons and/or pairs), or in electromagnetic form (Poynting flux). While the total observable flux may be indistinguishable in both cases, its polarization properties are expected to differ markedly. The prompt emission and afterglow polarization are also a powerful diagnostic of the jet geometry. Again, with subtle and hardly detectable differences in the output flux, we have distinct polarization predictions. In this review we briefly describe the theoretical scenarios that have been developed following the observations, and the now large observational datasets that for the prompt and the afterglow phases are available. Possible implications of polarimetric measurements for quantum gravity theory testing are discussed, and future perspectives for the field briefly ...

  10. Echo Emission From Dust Scattering and X-Ray Afterglows of Gamma-Ray Bursts

    CERN Document Server

    Shao, L; Mirabal, N

    2007-01-01

    We investigate the effect of X-ray echo emission in gamma-ray bursts (GRBs). We find that the echo emission can provide an alternative way of understanding X-ray shallow decays and jet breaks. In particular, a shallow decay followed by a "normal" decay and a further rapid decay of X-ray afterglows can be together explained as being due to the echo from prompt X-ray emission scattered by dust grains in a massive wind bubble around a GRB progenitor. We also introduce an extra temporal break in the X-ray echo emission. By fitting the afterglow light curves, we can measure the locations of the massive wind bubbles, which will bring us closer to finding the mass loss rate, wind velocity, and the age of the progenitors prior to the GRB explosions.

  11. Exploring the canonical behaviour of long gamma-ray bursts using an intrinsic multi-wavelength afterglow correlation

    CERN Document Server

    Oates, S R; De Pasquale, M; Page, M J; Castro-Tirado, A J; Gorosabel, J; Smith, P J; Breeveld, A A; Kuin, N P M

    2015-01-01

    In this paper we further investigate the relationship, reported by Oates et al., 2012, between the optical/UV afterglow luminosity (measured at restframe 200s) and average afterglow decay rate (measured from restframe 200s onwards) of long duration Gamma-ray Bursts (GRBs). We extend the analysis by examining the X-ray light curves, finding a consistent correlation. We therefore explore how the parameters of these correlations relate to the prompt emission phase and, using a Monte Carlo simulation, explore whether these correlations are consistent with predictions of the standard afterglow model. We find significant correlations between: $\\rm log\\;L_{O,200\\rm{s}}$ and $\\rm log\\;L_{X,200\\rm{s}}$; $\\alpha_{O,>200\\rm{s}}$ and $\\alpha_{X,>200\\rm{s}}$, consistent with simulations. The model also predicts relationships between $\\rm log\\;E_{iso}$ and $\\rm log\\;L_{200\\rm{s}}$, however, while we find such relationships in the observed sample, the slope of the linear regression is shallower than that simulated and incon...

  12. Temporal variability of GRB early X-ray afterglows and GRB080319B prompt emission

    CERN Document Server

    Margutti, R; Chincarini, G; Pasotti, F; Covino, S; Mao, J

    2008-01-01

    We performed the first systematic search for the minimum variability time scale between 0.3 and 10 keV studying the 28 brightest early (<3000 s) afterglows detected by Swift-XRT up to March 2008. We adopt the power spectrum analysis in the time domain: unlike the Fourier spectrum, this is suitable to study the rms variations at different time-scales. We find that early XRT afterglows show variability in excess of the Poissonian noise level on time-scales as short as about 1 s (rest frame value), with the shortest t_{min} associated with the highest energy band. The gamma-ray prompt emission of GRB080319B shows a characteristic average variability time-scale t_{var} of about 1s; this parameter undergoes a remarkable evolution during the prompt emission (BAT observation).

  13. First limits on the very-high energy gamma-ray afterglow emission of a fast radio burst. H.E.S.S. observations of FRB 150418

    Science.gov (United States)

    H. E. S. S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Andersson, T.; Angüner, E. O.; Arakawa, M.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Büchele, M.; Bulik, T.; Capasso, M.; Carr, J.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Chrétien, M.; Coffaro, M.; Colafrancesco, S.; Cologna, G.; Condon, B.; Conrad, J.; Cui, Y.; Davids, I. D.; Decock, J.; Degrange, B.; Deil, C.; Devin, J.; Dewilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O.'c.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Iwasaki, H.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jogler, T.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katsuragawa, M.; Katz, U.; Kerszberg, D.; Khangulyan, D.; Khélifi, B.; Kieffer, M.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morå, K.; Moulin, E.; Murach, T.; Nakashima, S.; de Naurois, M.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Öttl, S.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reimer, A.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Richter, S.; Rieger, F.; Romoli, C.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Saito, S.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seglar-Arroyo, M.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stycz, K.; Sushch, I.; Takahashi, T.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tsuji, N.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Żywucka, N.; Superb Collaboration; Jankowski, F.; Keane, E. F.; Petroff, E.

    2017-01-01

    Aims: Following the detection of the fast radio burst FRB150418 by the SUPERB project at the Parkes radio telescope, we aim to search for very-high energy gamma-ray afterglow emission. Methods: Follow-up observations in the very-high energy gamma-ray domain were obtained with the H.E.S.S. imaging atmospheric Cherenkov telescope system within 14.5 h of the radio burst. Results: The obtained 1.4 h of gamma-ray observations are presented and discussed. At the 99% C.L. we obtained an integral upper limit on the gamma-ray flux of Φγ(E > 350 GeV) energy were derived and used to constrain the intrinsic high-energy afterglow emission of FRB 150418. Conclusions: No hints for high-energy afterglow emission of FRB 150418 were found. Taking absorption on the extragalactic background light into account and assuming a distance of z = 0.492 based on radio and optical counterpart studies and consistent with the FRB dispersion, we constrain the gamma-ray luminosity at 1 TeV to L < 5.1 × 1047 erg/s at 99% C.L.

  14. First limits on the very-high energy gamma-ray afterglow emission of a fast radio burst: H.E.S.S. observations of FRB 150418

    CERN Document Server

    :,; Abramowski, A; Aharonian, F; Benkhali, F Ait; Akhperjanian, A G; Andersson, T; Angüner, E O; Arakawa, M; Arrieta, M; Aubert, P; Backes, M; Balzer, A; Barnard, M; Becherini, Y; Tjus, J Becker; Berge, D; Bernhard, S; Bernlöhr, K; Blackwell, R; Böttcher, M; Boisson, C; Bolmont, J; Bordas, P; Bregeon, J; Brun, F; Brun, P; Bryan, M; Büchele, M; Bulik, T; Capasso, M; Carr, J; Casanova, S; Cerruti, M; Chakraborty, N; Chalme-Calvet, R; Chaves, R C G; Chen, A; Chevalier, J; Chrétien, M; Coffaro, M; Colafrancesco, S; Cologna, G; Condon, B; Conrad, J; Cui, Y; Davids, I D; Decock, J; Degrange, B; Deil, C; Devin, J; deWilt, P; Dirson, L; Djannati-Ataï, A; Domainko, W; Donath, A; Drury, L O'C; Dutson, K; Dyks, J; Edwards, T; Egberts, K; Eger, P; Ernenwein, J -P; Eschbach, S; Farnier, C; Fegan, S; Fern, M V; Fiasson, A; Fontaine, G; Förster, A; Funk, S; Füßling, M; Gabici, S; Gajdus, M; Gallant, Y A; Garrigoux, T; Giavitto, G; Giebels, B; Glicenstein, J F; Gottschall, D; Goyal, A; Grondin, M -H; Hahn, J; Haupt, M; Hawkes, J; Heinzelmann, G; Henri, G; Hermann, G; Hervet, O; Hinton, J A; Hofmann, W; Hoischen, C; Holler, M; Horns, D; Ivascenko, A; Iwasaki, H; Jacholkowska, A; Jamrozy, M; Janiak, M; Jankowsky, D; Jankowsky, F; Jingo, M; Jogler, T; Jouvin, L; Jung-Richardt, I; Kastendieck, M A; Katarzyński, K; Katsuragawa, M; Katz, U; Kerszberg, D; Khangulyan, D; Khélifi, B; Kieffer, M; King, J; Klepser, S; Klochkov, D; Kluźniak, W; Kolitzus, D; Komin, Nu; Kosack, K; Krakau, S; Kraus, M; Krüger, P P; Laffon, H; Lamanna, G; Lau, J; Lees, J -P; Lefaucheur, J; Lefranc, V; Lemière, A; Lemoine-Goumard, M; Lenain, J -P; Leser, E; Lohse, T; Lorentz, M; Liu, R; López-Coto, R; Lypova, I; Mar, V; Marcowith, A; Mariaud, C; Marx, R; Maurin, G; Maxted, N; Mayer, M; Meintjes, P J; Meyer, M; Mitchell, A M W; Moderski, R; Mohamed, M; Mohrmann, L; Morå, K; Moulin, E; Murach, T; Nakashima, S; de Naurois, M; Niederwanger, F; Niemiec, J; Oakes, L; O'Brien, P; Odaka, H; Öttl, S; Ohm, S; Ostrowski, M; Oya, I; Padovani, M; Panter, M; Parsons, R D; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perennes, C; Petrucci, P -O; Peyaud, B; Piel, Q; Pita, S; Poon, H; Prokhorov, D; Prokoph, H; Pühlhofer, G; Punch, M; Quirrenbach, A; Raab, S; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Richter, S; Rieger, F; Romoli, C; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Saito, S; Salek, D; Sanchez, D A; Santangelo, A; Sasaki, M; Schlickeiser, R; Schüssler, F; Schulz, A; Schwanke, U; Schwemmer, S; Seglar-Arroyo, M; Settimo, M; Seyffert, A S; Shafi, N; Shilon, I; Simoni, R; Sol, H; Spanier, F; Spengler, G; Spies, F; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stycz, K; Sushch, I; Takahashi, T; Tavernet, J -P; Tavernier, T; Taylor, A M; Terrier, R; Tibaldo, L; Tiziani, D; Tluczykont, M; Trichard, C; Tsuji, N; Tuffs, R; Uchiyama, Y; van der Walt, D J; van Eldik, C; van Rensburg, C; van Soelen, B; Vasileiadis, G; Veh, J; Venter, C; Viana, A; Vincent, P; Vink, J; Voisin, F; Völk, H J; Vuillaume, T; Wadiasingh, Z; Wagner, S J; Wagner, P; Wagner, R M; White, R; Wierzcholska, A; Willmann, P; Wörnlein, A; Wouters, D; Yang, R; Zabalza, V; Zaborov, D; Zacharias, M; Zanin, R; Zdziarski, A A; Zech, A; Zefi, F; Ziegler, A; Żywucka, N; :,; Jankowski, F; Keane, E F; Petroff, E

    2016-01-01

    Aims: Following the detection of the fast radio burst FRB150418 by the SUPERB project at the Parkes radio telescope, we aim to search for very-high energy gamma-ray afterglow emission. Methods: Follow-up observations in the very-high energy gamma-ray domain were obtained with the H.E.S.S. imaging atmospheric Cherenkov telescope system within 14.5 hours of the radio burst. Results: The obtained 1.4 hours of gamma-ray observations are presented and discussed. At the 99 % C.L. we obtained an integral upper limit on the gamma-ray flux of (E>350 GeV) < 1.33 x 10^-8 m^-2s^-1. Differential flux upper limits as function of the photon energy were derived and used to constrain the intrinsic high-energy afterglow emission of FRB 150418. Conclusions: No hints for high-energy afterglow emission of FRB 150418 were found. Taking absorption on the extragalactic background light into account and assuming a distance of z = 0.492 based on radio and optical counterpart studies and consistent with the FRB dispersion, we constr...

  15. Electromagnetic Afterglows Associated with Gamma-Ray Emission Coincident with Binary Black Hole Merger Event GW150914

    CERN Document Server

    Yamazaki, Ryo; Ohira, Yutaka

    2016-01-01

    Fermi Gamma-ray Burst Monitor detected gamma-ray emission 0.4 sec after a binary black-hole merger event, GW150914. We show that the gamma-ray emission is caused by a relativistic outflow with Lorentz factor larger than 10. Subsequently debris outflow pushes ambient gas to form a shock, which is responsible for the afterglow synchrotron emission. We find that the fluxes of radio and optical afterglows increase from about $10^7$ sec to at least $\\sim10$ yr after the burst trigger. Further follow-up observations in the radio and optical/infrared bands are encouraged. Detection of afterglows will localize the sky position of the gravitational-wave and the gamma-ray emissions and it will support the physical association between them.

  16. Plastic damping of Alfv\\'en waves in magnetar flares and delayed afterglow emission

    CERN Document Server

    Li, Xinyu

    2015-01-01

    Magnetar flares generate Alfv\\'en waves bouncing in the closed magnetosphere with energy up to $\\sim 10^{46}$ erg. We show that on a 10-ms timescale the waves are transmitted into the star and form a compressed packet of high energy density. This packet strongly shears the stellar crust and initiates a plastic flow, heating the crust and melting it hundreds of meters below the surface. A fraction of the deposited plastic heat is eventually conducted to the stellar surface, contributing to the surface afterglow months to years after the flare. A large fraction of heat is lost to neutrino emission or conducted into the core of the neutron star.

  17. Gamma-ray Burst Reverse Shock Emission in Early Radio Afterglows

    Science.gov (United States)

    Resmi, Lekshmi; Zhang, Bing

    2016-07-01

    Reverse shock (RS) emission from gamma-ray bursts is an important tool in investigating the nature of the ejecta from the central engine. If the magnetization of the ejecta is not high enough to suppress the RS, a strong RS emission component, usually peaking in the optical/IR band early on, would provide an important contribution to early afterglow light curve. In the radio band, synchrotron self-absorption may suppress early RS emission and also delay the RS peak time. In this paper, we calculate the self-absorbed RS emission in the radio band under different dynamical conditions. In particular, we stress that the RS radio emission is subject to self-absorption in both RSs and forward shocks (FSs). We calculate the ratio between the RS to FS flux at the RS peak time for different frequencies, which is a measure of the detectability of the RS emission component. We then constrain the range of physical parameters for a detectable RS, in particular the role of magnetization. We notice that unlike optical RS emission which is enhanced by moderate magnetization, moderately magnetized ejecta do not necessarily produce a brighter radio RS due to the self-absorption effect. For typical parameters, the RS emission component would not be detectable below 1 GHz unless the medium density is very low (e.g., n < 10-3 cm-3 for the interstellar medium and A * < 5 × 10-4 for wind). These predictions can be tested using the afterglow observations from current and upcoming radio facilities such as the Karl G. Jansky Very Large Array, the Low-Frequency Array, the Five Hundred Meter Aperture Spherical Telescope, and the Square Kilometer Array.

  18. Early emission of rising optical afterglows: The case of GRB 060904B and GRB 070420

    CERN Document Server

    Klotz, A; Stratta, G; Galli, A; Corsi, A; Preger, B; Cutini, S; Pelangeon, A; Atteia, J L; Boër, M; Piro, L

    2008-01-01

    We present the time-resolved optical emission of gamma-ray bursts GRB 060904B and GRB 070420 during their prompt and early afterglow phases. We used time resolved photometry from optical data taken by the TAROT telescope and time resolved spectroscopy at high energies from the Swift spacecraft instrument. The optical emissions of both GRBs are found to increase from the end of the prompt phase, passing to a maximum of brightness at t_{peak}=9.2 min and 3.3 min for GRB 060904B and GRB 070420 respectively and then decrease. GRB 060904B presents a large optical plateau and a very large X-ray flare. We argue that the very large X-flare occurring near t_{peak} is produced by an extended internal engine activity and is only a coincidence with the optical emission. GRB 070420 observations would support this idea because there was no X-flare during the optical peak. The nature of the optical plateau of GRB 060904B is less clear and might be related to the late energy injection.

  19. Synchrotron and inverse-Compton emissions from pairs formed in GRB afterglows (analytical treatment)

    CERN Document Server

    Panaitescu, A

    2014-01-01

    We calculate the synchrotron and inverse-Compton emissions from pairs formed in GRB afterglows from high-energy photons (above 100 MeV), assuming a power-law photon spectrum C_nu ~ nu^{-2} and considering only the pairs generated from primary high-energy photons. The essential properties of these pairs (number, minimal energy, cooling energy, distribution with energy) and of their emission (peak flux, spectral breaks, spectral slope) are set by the observables GeV fluence Phi (t) = Ft and spectrum, and by the Lorentz factor Gamma and magnetic field B of the source of high-energy photons, at observer-time t. Optical and X-ray pseudo--light-curves F_nu (Gamma) are calculated for given B; proper synchrotron self-Compton light-curves are calculated by setting the dynamics Gamma(t) of the high-energy photons source to be that of a decelerating, relativistic shock. It is found that the emission from pairs can accommodate the flux and decays of the optical flashes measured during the prompt (GRB) phase and of the fa...

  20. THERMAL EMISSIONS SPANNING THE PROMPT AND THE AFTERGLOW PHASES OF THE ULTRA-LONG GRB 130925A

    Energy Technology Data Exchange (ETDEWEB)

    Basak, Rupal [Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw (Poland); Rao, A. R., E-mail: rupal@camk.edu.pl, E-mail: arrao@tifr.res.in [Tata Institute of Fundamental Research, Mumbai-400005, India. (India)

    2015-07-01

    GRB 130925A is an ultra-long gamma-ray burst (GRB), and it shows clear evidence for thermal emission in the soft X-ray data of the Swift/X-ray Telescope (XRT; ∼0.5 keV), lasting until the X-ray afterglow phase. Due to the long duration of the GRB, the burst could be studied in hard X-rays with high-resolution focusing detectors (NuSTAR). The blackbody temperature, as measured by the Swift/XRT, shows a decreasing trend until the late phase (Piro et al.) whereas the high-energy data reveal a significant blackbody component during the late epochs at an order of magnitude higher temperature (∼5 keV) compared to contemporaneous low energy data (Bellm et al.). We resolve this apparent contradiction by demonstrating that a model with two black bodies and a power law (2BBPL) is consistent with the data right from the late prompt emission to the afterglow phase. Both blackbodies show a similar cooling behavior up to late times. We invoke a structured jet, having a fast spine and a slower sheath layer, to identify the location of these blackbodies. Independent of the physical interpretation, we propose that the 2BBPL model is a generic feature of the prompt emission of all long GRBs, and the thermal emission found in the afterglow phase of different GRBs reflects the lingering thermal component of the prompt emission with different timescales. We strengthen this proposal by pointing out a close similarity between the spectral evolutions of this GRB and GRB 090618, a source with significant wide band data during the early afterglow phase.

  1. Prompt and Afterglow Emission Properties of Gamma-Ray Bursts with Spectroscopically Identified Supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Yuki; Ramirez-Ruiz, E.; Granot, J.; Kouveliotou, C.; Woosley, S.E.; Patel, S.K.; Rol, E.; Zand, J.J.M.in' t; a; Wijers, R.A.M.J.; Strom, R.; /USRA, Huntsville

    2006-07-12

    We present a detailed spectral analysis of the prompt and afterglow emission of four nearby long-soft gamma-ray bursts (GRBs 980425, 030329, 031203, and 060218) that were spectroscopically found to be associated with type Ic supernovae, and compare them to the general GRB population. For each event, we investigate the spectral and luminosity evolution, and estimate the total energy budget based upon broadband observations. The observational inventory for these events has become rich enough to allow estimates of their energy content in relativistic and sub-relativistic form. The result is a global portrait of the effects of the physical processes responsible for producing long-soft GRBs. In particular, we find that the values of the energy released in mildly relativistic outflows appears to have a significantly smaller scatter than those found in highly relativistic ejecta. This is consistent with a picture in which the energy released inside the progenitor star is roughly standard, while the fraction of that energy that ends up in highly relativistic ejecta outside the star can vary dramatically between different events.

  2. Prompt and afterglow X-ray emission from the X-Ray Flash of 2002 April 27

    CERN Document Server

    Amati, L; in 't Zand, J J M; Capalbi, M; Landi, R; Soffitta, P; Vetere, L; Antonelli, L A; Costa, E; Del Sordo, S; Feroci, M; Guidorzi, C; Heise, J; Masetti, N; Montanari, E; Nicastro, L; Palazzi, E; Piro, L

    2004-01-01

    We report on the X-ray observations of the X-ray flash (XRF) which occurred on 2002 April 27, three days before BeppoSAX was switched off. The event was detected with the BeppoSAX Wide Field Cameras but not with the Gamma ray Burst Monitor. A follow-up observation with the BeppoSAX Narrow Field Instruments was soon performed and a candidate afterglow source was discovered. We present the results obtained. We also include the results obtained from the observations of the XRF field with the Chandra X-ray satellite. The spectral analysis of the prompt emission shows that the peak energy of the EF(E) spectrum is lower than 5.5 keV, with negligible spectral evolution. The X-ray afterglow spectrum is consistent with a power law model with photon index of about 2, while the 2-10 keV flux fades as a power law with a decay index -1.33. Both these indices are typical of GRBs. A very marginal excess around 4.5-5 keV is found in the afterglow spectrum measured by BeppoSAX . As for many GRBs, the extrapolation of the 2-10...

  3. A Correlation between the Intrinsic Brightness and Average Decay Rate of Gamma-Ray Burst X-Ray Afterglow Light Curves

    Science.gov (United States)

    Racusin, J. L.; Oates, S. R.; de Pasquale, M.; Kocevski, D.

    2016-07-01

    We present a correlation between the average temporal decay ({α }{{X},{avg},\\gt 200{{s}}}) and early-time luminosity ({L}{{X},200{{s}}}) of X-ray afterglows of gamma-ray bursts as observed by the Swift X-ray Telescope. Both quantities are measured relative to a rest-frame time of 200 s after the γ-ray trigger. The luminosity-average decay correlation does not depend on specific temporal behavior and contains one scale-independent quantity minimizing the role of selection effects. This is a complementary correlation to that discovered by Oates et al. in the optical light curves observed by the Swift Ultraviolet Optical Telescope. The correlation indicates that, on average, more luminous X-ray afterglows decay faster than less luminous ones, indicating some relative mechanism for energy dissipation. The X-ray and optical correlations are entirely consistent once corrections are applied and contamination is removed. We explore the possible biases introduced by different light-curve morphologies and observational selection effects, and how either geometrical effects or intrinsic properties of the central engine and jet could explain the observed correlation.

  4. On the Lack of a Radio Afterglow from Some Gamma-ray Bursts - Insight into Their Progenitors?

    CERN Document Server

    Lloyd-Ronning, Nicole M

    2016-01-01

    We investigate the intrinsic properties of a sample of bright (E_iso > 10^52 erg) gamma-ray bursts, comparing those with and without radio afterglows. We find that the sample of bursts with no radio afterglows has a significantly shorter mean intrinsic duration of the prompt gamma-ray radiation, and the distribution of this duration is significantly different from those bursts with a radio afterglow. Although the sample with no radio afterglow has on average lower isotropic energy, the lack of radio afterglow does not appear to be a result of simply energetics of the burst, but a reflection of a separate physical phenomenon likely related to the circumburst density profile. We also find a weak correlation between the isotropic $\\gamma-$ray energy and intrinsic duration in the sample with no radio afterglow, but not in the sample which have observed radio afterglows. We give possible explanations for why there may exist a sample of GRBs with no radio afterglow depending on whether the radio emission comes from...

  5. NuSTARobservations of grb 130427a establish a single component synchrotron afterglow origin for the late optical to multi-gev emission

    DEFF Research Database (Denmark)

    Kouveliotou, C.; Granot, J.; Racusin, J. L.

    2013-01-01

    GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic Telescope ARray (NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (simil...

  6. Thermal Emissions Spanning the Prompt and the Afterglow Phase of the Ultra-long GRB 130925A

    CERN Document Server

    Basak, Rupal

    2015-01-01

    GRB 130925A is an ultra-long GRB, and it shows clear evidences for a thermal emission in the soft X-ray data of \\emph{Swift}/XRT ($\\sim0.5$\\,keV), lasting till the X-ray afterglow phase. Due to the long duration of the GRB, the burst could be studied in hard X-rays with high-resolution focusing detectors (\\emph{NuSTAR}). The blackbody temperature, as measured by the \\emph{Swift}/XRT, shows a decreasing trend till the late phase (Piro et al. 2014) whereas the high-energy data reveals a significant blackbody component during the late epochs at an order of magnitude higher temperature ($\\sim5$\\,keV), as compared to the contemporaneous low energy data (Bellm et al. 2014). We resolve this apparent contradiction by demonstrating that a model with two black bodies and a power-law (2BBPL) is consistent with the data right from the late prompt emission to the afterglow phase. Both the blackbodies show a similar cooling behaviour upto the late time. We invoke a structured jet, having a fast spine and a slower sheath la...

  7. Tail Emission from a Ring-like Jet: Its Application to Shallow Decays of Early Afterglows and GRB 050709

    Institute of Scientific and Technical Information of China (English)

    Yuan-Chuan Zou; Zi-Gao Dai

    2006-01-01

    Similar to the case of pulsars the magnetic axis and the spin axis of gamma-ray burst sources may not lie on the same line. This may cause the formation of a ring-like jet due to collimation of the precessing magnetic axis. We analyze the tail emission from such a jet,and find that it has a shallow decay phase with a temporal index of -1/9 if the Lorentz factor of the ejecta is not very high, which is consistent with the shallow decay phase of some early X-ray afterglow detected by Swift. The ring-like jet has a tail cusp with sharp rising and very sharp decay. This effect can provide an explanation for the re-brightening and sharp decay of the X-ray afterglowof GRB 050709.

  8. THERMAL EMISSION IN THE EARLY X-RAY AFTERGLOWS OF GAMMA-RAY BURSTS: FOLLOWING THE PROMPT PHASE TO LATE TIMES

    Energy Technology Data Exchange (ETDEWEB)

    Friis, Mette [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland); Watson, Darach, E-mail: mef4@hi.is, E-mail: darach@dark-cosmology.dk [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark)

    2013-07-01

    Thermal radiation, peaking in soft X-rays, has now been detected in a handful of gamma-ray burst (GRB) afterglows and has to date been interpreted as shock break-out of the GRB's progenitor star. We present a search for thermal emission in the early X-ray afterglows of a sample of Swift bursts selected by their brightness in X-rays at early times. We identify a clear thermal component in eight GRBs and track the evolution. We show that at least some of the emission must come from highly relativistic material since two show an apparent super-luminal expansion of the thermal component. Furthermore, we determine very large luminosities and high temperatures for many of the components-too high to originate in a supernova shock break-out. Instead, we suggest that the component may be modeled as late photospheric emission from the jet, linking it to the apparently thermal component observed in the prompt emission of some GRBs at gamma-ray and hard X-ray energies. By comparing the parameters from the prompt emission and the early afterglow emission, we find that the results are compatible with the interpretation that we are observing the prompt quasi-thermal emission component in soft X-rays at a later point in its evolution.

  9. The circumburst environment of a FRED GRB: study of the prompt emission and X-ray/optical afterglow of GRB 051111

    CERN Document Server

    Guidorzi, C; Kobayashi, S; Mundell, C G; Rol, E; Bode, M F; Carter, D; La Parola, V; Melandri, A; Monfardini, A; Mottram, C J; O'Brien, P T; Page, K L; Sakamoto, T; Smith, R J; Steele, I A; Tanvir, N R

    2006-01-01

    We report a multi-wavelength analysis of the prompt emission and early afterglow of GRB051111 and discuss its properties in the context of current fireball models. The detection of GRB051111 by the Burst Alert Telescope on-board Swift triggered early BVRi' observations with the 2-m robotic Faulkes Telescope North in Hawaii, as well as X-ray observations with the Swift X-Ray Telescope. The prompt gamma-ray emission shows a classical FRED profile. The optical afterglow light curves are fitted with a broken power law, with alpha_1=0.35 to alpha_2=1.35 and a break time around 12 minutes after the GRB. Although contemporaneous X-ray observations were not taken, a power law connection between the gamma-ray tail of the FRED temporal profile and the late XRT flux decay is feasible. Alternatively, if the X-ray afterglow tracks the optical decay, this would represent one of the first GRBs for which the canonical steep-shallow-normal decay typical of early X-ray afterglows has been monitored optically. We present a deta...

  10. Afterglow Emission of Er3+, Ho3+ and Tm3+ in Gadolinium Oxysulfide%Er3+,Ho3+和Tm3+硫氧化钆中的余辉发光

    Institute of Scientific and Technical Information of China (English)

    刘应亮; 宋春燕; 张静娴; 袁定胜; 黄浪欢; 容建华; 张俊文

    2005-01-01

    The new Er3+, Ho3+ and Tm3+ doped gadolinium oxysulfide phosphors with the long afterglow emission were synthesized by solid-state reaction method. The synthesized phosphors were characterized by X-ray diffraction. The excitation and photolumineseenee spectra, afterglow spectra and afterglow decay curve were examined by fluorescence spectroscopy. The afterglow spectra of Gd2O2S:Er3+, Mg, Ti showed typical transitions of Er3+ at 528(2H11/2→4I15/2), 548 (4S3/2 →4I15/2) and 669 nm (4F9/2→4I15/2). In the afterglow spectra of Gd2O2S: Ho3+, Mg, Ti,typical transitions of Ho3+ at 546 nm (5S2→5I8), 651 and 661 nm (2F5→5I8) were observed. In Gd2O2S:Tm3+, Mg,Ti, the afterglow emission at 800 nm (1G4→3H5) of Tm3+ was seen. The meehnism and model of afterglow energy transfer were proposed.

  11. Constraint on the counter-jet emission in gamma-ray burst afterglows from GRB 980703

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We present a numerical investigation of emission from the receding jet of gamma-ray bursts.It is found that the peak time of the receding jet emission is significantly affected by synchrotron self-absorption in radio wavelengths.However,the receding jet component is generally very weak.It is observable mainly for those nearby events in a dense environment.Although GRB 980703 has been observed in radio wavelengths for more than 1000 days,we argue that the receding jet emission still has not been detected for this event.Actually,it is completely submerged by the host galaxy.

  12. Probing the environment of gravitational wave transient sources with TeV afterglow emission

    CERN Document Server

    Zhu, Qin-Yu

    2016-01-01

    Recently, Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) detected gravitational wave (GW) transients from mergers of binary black holes (BHs). The system may also produce a wide-angle, relativistic outflow if the claimed short GRB detected by GBM is in real association with GW 150914. It was suggested that mergers of double neutron stars (or neutron star-black hole binaries), another promising source of GW transients, also produce fast, wide-angle outflows. In this paper, we calculate the high-energy gamma-ray emission arising from the blast waves driven by these wide-angle outflows. We find that TeV emission arising from the inverse-Compton process in the relativistic outflow resulted from mergers of binary BHs similar to those in GW 150914 could be detectable by ground-based IACT telescopes such as Cherenkov Telescope Array (CTA) if the sources occur in { a dense medium with density $n > 0.3 cm^{-3}$}. For neutron star-neutron star (NS-NS) and NS-BH mergers, TeV emission from the wide-...

  13. A COMPREHENSIVE STUDY OF GAMMA-RAY BURST OPTICAL EMISSION. II. AFTERGLOW ONSET AND LATE RE-BRIGHTENING COMPONENTS

    Energy Technology Data Exchange (ETDEWEB)

    Liang Enwei; Li Liang; Liang Yunfeng; Tang Qingwen; Chen Jiemin; Lu Ruijing; Lue Lianzhong [Department of Physics and GXU-NAOC Center for Astrophysics and Space Sciences, Guangxi University, Nanning 530004 (China); Gao He; Zhang, Bing; Lue Houjun [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States); Wu Xuefeng [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Yi Shuangxi; Dai Zigao [School of Astronomy and Space Science, Nanjing University, Nanjing, Jiangsu 210093 (China); Zhang Jin; Wei Jianyan, E-mail: lew@gxu.edu.cn, E-mail: zhang@physics.unlv.edu [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2013-09-01

    We continue our systematic statistical study of various components of gamma-ray burst (GRB) optical light curves. We decompose the early onset bump and the late re-brightening bump with empirical fits and analyze their statistical properties. Among the 146 GRBs that have well-sampled optical light curves, the onset and re-brightening bumps are observed in 38 and 26 GRBs, respectively. It is found that the typical rising and decaying slopes for both the onset and re-brightening bumps are {approx}1.5 and {approx} - 1.15, respectively. No early onset bumps in the X-ray band are detected to be associated with the optical onset bumps, while an X-ray re-brightening bump is detected for half of the re-brightening optical bumps. The peak luminosity is anti-correlated with the peak time L{sub p}{proportional_to}t{sub p}{sup -1.81{+-}0.32} for the onset bumps and L{sub p}{proportional_to}t{sub p}{sup -0.83{+-}0.17} for the re-brightening bumps. Both L{sub p} and the isotropic energy release of the onset bumps are correlated with E{sub {gamma},iso}, whereas no similar correlation is found for the re-brightening bumps. These results suggest that the afterglow onset bumps are likely due to the deceleration of the GRB fireballs. Taking the onset bumps as probes for the properties of the fireballs and their ambient medium, we find that the typical power-law index of the relativistic electrons is 2.5 and the medium density profile behaves as n{proportional_to}r {sup -1} within the framework of the synchrotron external shock models. With the medium density profile obtained from our analysis, we also confirm the correlation between the initial Lorentz factor ({Gamma}{sub 0}) and E{sub iso,{gamma}} in our previous work. The jet component that produces the re-brightening bump seems to be on-axis and independent of the prompt emission jet component. Its typical kinetic energy budget would be about one order of magnitude larger than the prompt emission component, but with a lower {Gamma

  14. Gamma-Ray Burst Early Afterglows

    CERN Document Server

    Zhang, B

    2005-01-01

    The successful launch and operation of NASA's Swift Gamma-Ray Burst Explorer open a new era for the multi-wavelength study of the very early afterglow phase of gamma-ray bursts (GRBs). GRB early afterglow information is essential to explore the unknown physical composition of GRB jets, the link between the prompt gamma-ray emission and the afterglow emission, the GRB central engine activity, as well as the immediate GRB environment. Here I review some of the recent theoretical efforts to address these problems and describe how the latest Swift data give answers to these outstanding questions.

  15. GRB 091208B: FIRST DETECTION OF THE OPTICAL POLARIZATION IN EARLY FORWARD SHOCK EMISSION OF A GAMMA-RAY BURST AFTERGLOW

    Energy Technology Data Exchange (ETDEWEB)

    Uehara, T.; Chiyonobu, S.; Fukazawa, Y.; Ikejiri, Y.; Itoh, R.; Komatsu, T.; Miyamoto, H.; Nagae, O.; Sakimoto, K.; Sasada, M.; Tanaka, H.; Yamanaka, M. [Department of Physical Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526 (Japan); Toma, K. [Department of Earth and Space Science, Osaka University, Toyonaka 560-0043 (Japan); Kawabata, K. S.; Mizuno, T.; Ohsugi, T.; Uemura, M. [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Inoue, T.; Yamashita, T. [Department of Physics and Mathematics, Aoyama Gakuin University, Fuchinobe, Chuou-ku, Sagamihara 252-5258 (Japan); Nakaya, H., E-mail: uehara@hep01.hepl.hiroshima-u.ac.jp [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan); and others

    2012-06-10

    We report that the optical polarization in the afterglow of GRB 091208B is measured at t = 149-706 s after the burst trigger, and the polarization degree is P = 10.4( {+-} 2.5%. The optical light curve at this time shows a power-law decay with index -0.75 {+-} 0.02, which is interpreted as the forward shock synchrotron emission, and thus this is the first detection of the early-time optical polarization in the forward shock (rather than that in the reverse shock reported by Steele et al.). This detection disfavors the afterglow model in which the magnetic fields in the emission region are random on the plasma skin depth scales, such as those amplified by the plasma instabilities, e.g., Weibel instability. We suggest that the fields are amplified by the magnetohydrodynamic instabilities, which would be tested by future observations of the temporal changes of the polarization degrees and angles for other bursts.

  16. Implications from the Upper Limit of Radio Afterglow Emission of FRB 131104/Swift J0644.5-5111

    Science.gov (United States)

    Gao, He; Zhang, Bing

    2017-02-01

    A γ-ray transient, Swift J0644.5-5111, has been claimed to be associated with FRB 131104. However, a long-term radio imaging follow-up observation only placed an upper limit on the radio afterglow flux of Swift J0644.5-5111. Applying the external shock model, we perform a detailed constraint on the afterglow parameters for the FRB 131104/Swift J0644.5-5111 system. We find that for the commonly used microphysics shock parameters (e.g., {ε }e=0.1, {ε }B=0.01, and p = 2.3), if the fast radio burst (FRB) is indeed cosmological as inferred from its measured dispersion measure (DM), the ambient medium number density should be ≤slant {10}-3 {{cm}}-3, which is the typical value for a compact binary merger environment but disfavors a massive star origin. Assuming a typical ISM density, one would require that the redshift of the FRB be much smaller than the value inferred from DM (z\\ll 0.1), implying a non-cosmological origin of DM. The constraints are much looser if one adopts smaller {ε }B and {ε }e values, as observed in some gamma-ray burst afterglows. The FRB 131104/Swift J0644.5-5111 association remains plausible. We critically discuss possible progenitor models for the system.

  17. GLAST Prospects for Swift-Era Afterglows

    Energy Technology Data Exchange (ETDEWEB)

    Gou, L.J.; /Penn State U., Astron. Astrophys.; Meszaros, P.; /Penn State U.

    2011-11-23

    We calculate the GeV spectra of gamma-ray burst afterglows produced by inverse Compton scattering of these objects sub-MeV emission. We improve on earlier treatments by using refined afterglow parameters and new model developments motivated by recent Swift observations. We present time-dependent GeV spectra for standard, constant-parameter models, as well as for models with energy injection and with time-varying parameters, for a range of burst parameters. We evaluate the limiting redshift to which such afterglows can be detected by the GLAST Large Area Telescope, as well as by AGILE.

  18. Observational Signatures of High-Energy Emission during the Shallow Decay Phase of Gamma-Ray Burst X-Ray Afterglows

    Science.gov (United States)

    Yu, Y. W.; Liu, X. W.; Dai, Z. G.

    2007-12-01

    The widely existing shallow decay phase of the X-ray afterglows of gamma-ray bursts (GRBs) is generally accepted to be due to long-lasting energy injection. The outflows carrying the injecting energy, based on the component that is dominant in energy, fall into two possible types: baryon-dominated and lepton-dominated ones. The former type of outflow could be ejecta that is ejected during the prompt phase of a GRB and consists of a series of baryonic shells with a distribution of Lorentz factors, and the latter type could be an electron-positron pair wind that is driven by the postburst central engine. We here provide a unified description for the dynamics of fireballs based on these two types of energy injection and calculate the corresponding high-energy photon emission by considering synchrotron radiation and inverse Compton scattering (including synchrotron self-Compton and combined inverse Compton) of electrons. We find that, in the two energy-injection models, there is a plateau (even a hump) in high-energy light curves during the X-ray shallow decay phase. In particular, a considerable fraction of the injecting energy in the lepton-dominated model can be shared by the long-lasting reverse shock since it is relativistic. Furthermore, almost all of the energy of the reverse shock is carried by leptons, and thus, the inverse Compton emission is enhanced dramatically. Therefore, this model predicts more significant high-energy afterglow emission than the baryon-dominated model. We argue that these observational signatures would be used to discriminate between different energy-injection models in the upcoming Gamma-Ray Large Area Space Telescope (GLAST) era.

  19. Implications from the upper limit of radio afterglow emission of FRB 131104/Swift J0644.5-5111

    CERN Document Server

    Gao, He

    2016-01-01

    A $\\gamma$-ray transient, Swift J0644.5-5111, has been claimed to be associated with FRB 131104. The $\\gamma$-ray energy output is estimated as $E_\\gamma \\approx 5\\times 10^{51}$\\,erg at the nominal $z\\approx 0.55$ redshift implied by the dispersion measure of FRB 131104. However, a long-term radio imaging follow-up observations only place an upper limit on the radio afterglow flux of Swift J0644.5-5111. Applying the external shock model, we make a detailed constraint on the afterglow parameters for the FRB 131104/Swift J0644.5-5111 system. We find that for the commonly used microphysics shock parameters (e.g., $\\epsilon_e=0.1$, $\\epsilon_B=0.01$ and $p=2.3$), if the redshift value inferred from the DM value is correct to order of magnitude (i.e., $z>0.1$), the ambient medium number density should be $\\leq 10^{-3}~\\rm{cm^{-3}}$, which is the typical value for a compact binary merger environment but disfavors a massive star origin. Assuming a typical ISM density, one would require that the redshift of the FRB ...

  20. The Strongly Polarized Afterglow of GRB 020405

    CERN Document Server

    Bersier, D F; Garnavich, P M; Holman, M J; Grav, T; Quinn, J; Kaluzny, J; Challis, P M; Bower, R G; Wilman, D J; Heyl, J S; Holland, S T; Hradecky, V; Jha, S; Stanek, K Z

    2003-01-01

    We report polarization measurements and photometry for the optical afterglow of the gamma-ray burst GRB 020405. We measured a highly significant 9.9% polarization (in V band) 1.3 days after the burst and argue that it is intrinsic to the GRB. The light curve decay is well fitted by a $t^{-1.72}$ power-law; we do not see any evidence for a break between 1.24 and 4.3 days after the burst. We discuss these measurements in the light of several models of GRB afterglows.

  1. Physics of the GRB 030328 afterglow and its environment

    NARCIS (Netherlands)

    Maiorano, E.; Masetti, N.; Palazzi, E.; Savaglio, S.; Rol, E.; Vreeswijk, P.M.; Pian, E.; Price, P.A.; Peterson, B.A.; Jelínek, M.; Amati, L.; Andersen, M.I.; Castro-Tirado, A.J.; Castro Cerón, J.M.; de Ugarte Postigo, A.; Frontera, F.; Fruchter, A.S.; Fynbo, J.P.U.; Gorosabel, J.; Henden, A.A.; Hjorth, J.; Jensen, B.L.; Klose, S.; Kouveliotou, C.; Masi, G.; Møller, P.; Nicastro, L.; Ofek, E.O.; Pandey, S.B.; Rhoads, J.E.; Tanvir, N.R.; Wijers, R.A.M.J.; van den Heuvel, E.P.J.

    2006-01-01

    Aims.To investigate the physical nature of the afterglow emission. We report on the photometric, spectroscopic and polarimetric observations of the optical afterglow of Gamma-Ray Burst (GRB) 030328 detected by HETE-2. Methods.Photometric, spectroscopic and polarimetric monitoring of the optical afte

  2. Afterglows from precursors in Gamma Ray Bursts. Application to the optical afterglow of GRB 091024

    CERN Document Server

    Nappo, F; Ghirlanda, G; Melandri, A; Nava, L; Burlon, D

    2014-01-01

    About 15% of Gamma Ray Bursts have precursors, i.e. emission episodes preceding the main event, whose spectral and temporal properties are similar to the main emission. We propose that precursors have their own fireball, producing afterglow emission due to the dissipation of the kinetic energy via external shock. In the time lapse between the precursor and the main event, we assume that the central engine is not completely turned off, but it continues to eject relativistic material at a smaller rate, whose emission is below the background level. The precursor fireball generates a first afterglow by the interaction with the external circumburst medium. Matter injected by the central engine during the "quasi-quiescent" phase replenishes the external medium with material in relativistic motion. The fireball corresponding to the main prompt emission episode crashes with this moving material, producing a second afterglow, and finally catches up and merges with the first precursor fireball. We apply this new model ...

  3. Fermi and Swift Gamma-Ray Burst Afterglow Population Studies

    Science.gov (United States)

    Racusin, Judith L.; Oates, S. R.; Schady, P.; Burrows, D. N.; dePasquale, M.; Donato, D.; Gehrels, N.; Koch, S.; McEnery, J.; Piran, T.; hide

    2011-01-01

    The new and extreme population of GRBs detected by Fermi -LAT shows several new features in high energy gamma-rays that are providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 6 years, it has been Swift that has provided the robust dataset of UV/optical and X-ray afterglow observations that opened many windows into components of GRB emission structure. The relationship between the LAT detected GRBs and the well studied, fainter, less energetic GRBs detected by Swift -BAT is only beginning to be explored by multi-wavelength studies. We explore the large sample of GRBs detected by BAT only, BAT and Fermi -GBM, and GBM and LAT, focusing on these samples separately in order to search for statistically significant differences between the populations, using only those GRBs with measured redshifts in order to physically characterize these objects. We disentangle which differences are instrumental selection effects versus intrinsic properties, in order to better understand the nature of the special characteristics of the LAT bursts.

  4. Critical Review of Basic Afterglow Concepts

    CERN Document Server

    Granot, Jonathan

    2008-01-01

    The long lived afterglow emission that follows gamma-ray bursts (GRBs) was predicted prior to its detection in 1997, in the X-rays, optical and radio. It is thought to arise from the shock that is driven into the external medium as the latter decelerates the relativistic outflow that drives the GRB, and persists well after most of the energy in the outflow is transferred to the shocked external medium. As the blast wave decelerates, the typical emission frequency shifts to longer wavelength. Recent observations following the launch of the Swift satellite challenge the traditional afterglow modeling and call into questions some of the basic underlying concepts. This brief review outlines some of the major strengths and weaknesses of the standard afterglow model, as well as some of the challenges that it faces in explaining recent data, and potential directions for future study that may eventually help overcome some of the current difficulties.

  5. Radio Afterglows of Gamma Ray Bursts

    Science.gov (United States)

    Resmi, Lekshmi

    2017-09-01

    This review focuses on the physics of Gamma Ray Bursts probed through their radio afterglow emission. Even though radio band is the least explored of the afterglow spectrum, it has played an important role in the progress of GRB physics, specifically in confirming the hypothesized relativistic effects. Currently radio astronomy is in the beginning of a revolution. The high sensitive Square Kilometer Array (SKA) is being planned, its precursors and pathfinders are about to be operational, and several existing instruments are undergoing upgradation. Thus, the afterglow results from detection statistics and follow up programs are expected to improve in the coming years. We list a few avenues unique to radio band which if explored to full potential have the promise to greatly contribute to the future of GRB physics.

  6. Afterglow Model for the Radio Emission from the Jetted Tidal Disruption Candidate Swift J1644+57

    CERN Document Server

    Metzger, Brian D; Mimica, Petar

    2011-01-01

    The recent transient event Swift J1644+57 has been interpreted as emission from a collimated relativistic jet, powered by the sudden onset of accretion onto a supermassive black hole following the tidal disruption of a star. Here we model the radio-microwave emission as synchrotron radiation produced by the shock interaction between the jet and the gaseous circumnuclear medium (CNM). At early times after the onset of the jet (t < 5-10 days) a reverse shock propagates through and decelerates the ejecta, while at later times the outflow approaches the Blandford-McKee self-similar evolution (possibly modified by additional late energy injection). The achromatic break in the radio light curve of J1644+57 is naturally explained as the transition between these phases. We show that the temporal indices of the pre- and post-break light curve are consistent with those predicted if the CNM has a wind-type radial density profile n ~ 1/r^2. The observed synchrotron frequencies and self-absorbed flux constrain the frac...

  7. Observational constraints on the afterglow of GRB 020531

    CERN Document Server

    Klotz, A H; Atteia, J L; Klotz, Alain; Boer, Michel; Atteia, Jean-Luc

    2003-01-01

    We present the data acquired by the TAROT automated observatory on the afterglow of GRB 020531. Up to now, no convincing afterglow emission has been reported for this short/hard GRB at any wavelength, including X-ray and optical. The combination of our early limits, with other published data allows us to put severe constraints on the afterglow magnitude and light curve. The limiting magnitude is 18.5 in R band, 88 minutes after the GRB, and the decay slope power law index could be larger than 2.2.

  8. Afterglow model for the radio emission from the jetted tidal disruption candidate Swift J1644+57

    Science.gov (United States)

    Metzger, Brian D.; Giannios, Dimitrios; Mimica, Petar

    2012-03-01

    The recent transient event Swift J1644+57 has been interpreted as emission from a collimated relativistic jet, powered by the sudden onset of accretion on to a supermassive black hole following the tidal disruption of a star. Here we model the radio-microwave emission as synchrotron radiation produced by the shock interaction between the jet and the gaseous circumnuclear medium (CNM). At early times after the onset of the jet (t≲ 5-10 d) a reverse shock propagates through and decelerates the ejecta, while at later times the outflow approaches the Blandford-McKee self-similar evolution (possibly modified by additional late energy injection). The achromatic break in the radio light curve of Swift J1644+57 is naturally explained as the transition between these phases. We show that the temporal indices of the pre- and post-break light curve are consistent with those predicted if the CNM has a wind-type radial density profile n∝r-2. The observed synchrotron frequencies and self-absorbed flux constrain the fraction of the post-shock thermal energy in relativistic electrons ɛe≈ 0.03-0.1, the CNM density at 1018 cm n18≈ 1-10 cm-3 and the initial Lorentz factor Γj≈ 10-20 and opening angle ? of the jet. Radio modelling thus provides robust independent evidence for a narrowly collimated outflow. Extending our model to the future evolution of Swift J1644+57, we predict that the radio flux at low frequencies (ν≲ few GHz) will begin to brighten more rapidly once the characteristic frequency νm crosses below the radio band after it decreases below the self-absorption frequency on a time-scale of months (indeed, such a transition may already have begun). Our results demonstrate that relativistic outflows from tidal disruption events provide a unique probe of the conditions in distant, previously inactive galactic nuclei, complementing studies of normal active galactic nuclei.

  9. Nonlinear Particle Acceleration and Thermal Particles in GRB Afterglows

    Science.gov (United States)

    Warren, Donald C.; Ellison, Donald C.; Barkov, Maxim V.; Nagataki, Shigehiro

    2017-02-01

    The standard model for GRB afterglow emission treats the accelerated electron population as a simple power law, N(E)\\propto {E}-p for p≳ 2. However, in standard Fermi shock acceleration, a substantial fraction of the swept-up particles do not enter the acceleration process at all. Additionally, if acceleration is efficient, then the nonlinear back-reaction of accelerated particles on the shock structure modifies the shape of the nonthermal tail of the particle spectra. Both of these modifications to the standard synchrotron afterglow impact the luminosity, spectra, and temporal variation of the afterglow. To examine the effects of including thermal particles and nonlinear particle acceleration on afterglow emission, we follow a hydrodynamical model for an afterglow jet and simulate acceleration at numerous points during the evolution. When thermal particles are included, we find that the electron population is at no time well fitted by a single power law, though the highest-energy electrons are; if the acceleration is efficient, then the power-law region is even smaller. Our model predicts hard–soft–hard spectral evolution at X-ray energies, as well as an uncoupled X-ray and optical light curve. Additionally, we show that including emission from thermal particles has drastic effects (increases by factors of 100 and 30, respectively) on the observed flux at optical and GeV energies. This enhancement of GeV emission makes afterglow detections by future γ-ray observatories, such as CTA, very likely.

  10. Limits on the TeV gamma-ray afterglow of fast radio bursts with H.E.S.S.

    Science.gov (United States)

    Schüssler, F.; Brun, F.; Pühlhofer, G.; Rowell, G.; Wagner, R.; H.E.S.S. Collaboration; Keane, E.; Petroff, E.; SUPERB Collaboration

    2017-01-01

    We here present the H.E.S.S. follow-up of Fast Radio Bursts (FRBs), millisecond-long, very strong radio pulses of yet unknown origin. The SUPERB (SUrvey for Pulsars and Extragalactic Radio Bursts) project at the Parkes radio observatory is able to detect these enigmatic events almost in real-time which allows triggering follow-up observations covering the full electromagnetic spectrum. The H.E.S.S. gamma-ray observatory is taking active part in this endeavor. Here we focus on data taken within hours of FRB 150418, which allow us to derive the first limits on gamma-ray afterglow emission of FRBs. Based on the identification of the potential host galaxy of this burst we are able to discuss absorption effects due to the extragalactic background light (EBL) and derive intrinsic, energy dependent limits on the gamma-ray afterglow.

  11. Gamma-ray emission spectrum from thermonuclear fusion reactions without intrinsic broadening

    DEFF Research Database (Denmark)

    Nocente, M.; Källne, J.; Salewski, Mirko

    2015-01-01

    First principle calculations of the gamma-ray energy spectrum arising from thermonuclear reactions without intrinsic broadening in fusion plasmas are presented, extending the theoretical framework needed to interpret measurements up to the accuracy level enabled by modern high resolution instrume......First principle calculations of the gamma-ray energy spectrum arising from thermonuclear reactions without intrinsic broadening in fusion plasmas are presented, extending the theoretical framework needed to interpret measurements up to the accuracy level enabled by modern high resolution...... information that can be extracted from the gamma-ray emission spectrum of fusion reactions without intrinsic broadening and are of relevance for applications to high performance plasmas of present and next generation devices....

  12. Methodology in the Afterglow

    Science.gov (United States)

    Hofsess, Brooke Anne

    2013-01-01

    My dissertation study seeks to understand how artist-teacher renewal may be nurtured through aesthetic experiential play in a Masters of Art Education degree program, and beyond, as my former students/participants and myself experience finding ourselves in its afterglow. "Aesthetic experiential play" could be described as a playful,…

  13. Optical afterglows of Gamma-Ray Bursts: peaks, plateaus, and possibilities

    CERN Document Server

    Panaitescu, A

    2010-01-01

    The optical light-curves of GRB afterglows display either peaks or plateaus. We identify 15 afterglows of the former type and 20 of the latter. Their optical energy release is similar and is correlated to the GRB output, the correlation being stronger for peaky afterglows. That suggests that the prompt (burst) and delayed emissions of peaky afterglows are from the same relativistic ejecta and that the optical emission of plateau afterglows arises more often from ejecta that did not produce the burst emission. Consequently, we propose that peaky optical afterglows are from impulsive ejecta releases and that plateau optical afterglows originate from long-lived engines, the break in the optical light-curve (peak or plateau end) marking the onset of the entire outflow deceleration. In the peak luminosity--peak time plane, the distribution of peaky afterglows displays an edge with L_p propto t_p^{-3}, which is more likely to arise from variations (among afterglows) in the ambient medium density. The fluxes and epo...

  14. Unusually rapid variability of the GRB000301C optical afterglow

    DEFF Research Database (Denmark)

    Masetti, N.; Bartolini, C.; Bernabei, S.;

    2000-01-01

    with BVI data has revealed complex behavior, with a long term flux decrease and various short time scale features superimposed. These features are uncommon among other observed afterglows. and might trace either intrinsic variability within the relativistic shock (re-acceleration and re...

  15. The Detectability of Orphan Afterglows

    CERN Document Server

    Piran, E N T

    2002-01-01

    The realization that GRBs release a rather constant amount of energy implies that the post jet-break afterglow evolution would be rather universal and for a given redshift they should be detected up to a fixed observer angle. We estimate the observed magnitude and the implied detectability of orphan afterglows. We show that orphan afterglows would be detectable only up to rather small ($\\sim 10^o$) angles away from the GRB jet axis. Thus a detection orphan afterglow would generally correspond to a "near-miss" of the GRB whose jet was pointing just slightly away from us. Both theoretical and phenomenological estimates of the rate of orphan afterglows suffer from a rather large uncertainty. With our "canonical" parameters we expect a dozen transients that would arise from orphan GRBs in the SDSS and a comparable number of transients in a dedicated 2M class telescope operating full time in an orphan afterglow search.

  16. Long afterglow of trivalent dysprosium doped strontium aluminate

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yuan Ming, E-mail: dongshanisland@126.com [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); Ma, Qing-lan [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); School of Electronics and Information, Nantong University, Jiangsu 226019 (China)

    2015-04-15

    Trivalent dysprosium doped strontium aluminate (SrA1{sub 2}O{sub 4}:Dy{sup 3+}) was synthesized via the sol–gel combustion method to realize green afterglow in the absence of Eu{sup 2+} luminescent centers. The morphology, crystal structure, photoluminescence and long afterglow of the SrAl{sub 2}O{sub 4}:Dy{sup 3+} were characterized with scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and photoluminescence spectroscopy, respectively. The bluish-green photoluminescence of SrAl{sub 2}O{sub 4}:Dy{sup 3+} consists of a broad emission band centered at about 520 nm and two characteristic emissions of Dy{sup 3+} ions centered at 480 and 575 nm, respectively. The green afterglow of SrAl{sub 2}O{sub 4}:Dy{sup 3+} is a broad emission band centered at around 520 nm, and the lifetime extracted from afterglow decay is found to be 53 s. The mechanism on the green afterglow from SrAl{sub 2}O{sub 4}:Dy{sup 3+} is discussed in terms of the possible defect levels in the host. - Highlights: • Broad band long-lasting afterglow is observed in SrAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. • Characteristic emissions of Dy{sup 3+} ions are superimposed on the broad PL of phosphors. • Dy{sup 3+} ions can also act as luminescent centers in addition to electron traps. • A mechanism on long afterglow of SrAl{sub 2}O{sub 4}:Dy{sup 3+} is proposed without Eu{sup 2+} activator.

  17. The Onset of Gamma-Ray Burst Afterglow

    Science.gov (United States)

    Kobayashi, Shiho; Zhang, Bing

    2007-02-01

    We discuss the reference time t0 of afterglow light curves in the context of the standard internal-external shock model. The decay index of early afterglow is very sensitive to the reference time one chooses. In order to understand the nature of early afterglow, it is essential to take a correct reference time. Our simple analytic model provides a framework for understanding special relativistic effects involved in early afterglow phase. We evaluate light curves of reverse shock emission as well as those of forward shock emission, based on full hydrodynamic calculations. We show that the reference time does not shift significantly even in the thick-shell case. For external shock emission components, measuring times from the beginning of the prompt emission is a good approximation and it does not cause an early steep decay. In the thin-shell case, the energy transfer time from fireball ejecta to ambient medium typically extends to thousands of seconds. This might be related to the shallow decay phases observed in early X-ray afterglow at least for some bursts.

  18. Altitudinal dependence of meteor radio afterglows measured via optical counterparts

    CERN Document Server

    Obenberger, K S; Dowell, J D; Schinzel, F K; Stovall, K; Sutton, E K; Taylor, G B

    2016-01-01

    Utilizing the all-sky imaging capabilities of the LWA1 radio telescope along with a host of all-sky optical cameras, we have now observed 44 optical meteor counterparts to radio afterglows. Combining these observations we have determined the geographic positions of all 44 afterglows. Comparing the number of radio detections as a function of altitude above sea level to the number of expected bright meteors we find a strong altitudinal dependence characterized by a cutoff below $\\sim$ 90 km, below which no radio emission occurs, despite the fact that many of the observed optical meteors penetrated well below this altitude. This cutoff suggests that wave damping from electron collisions is an important factor for the evolution of radio afterglows, which agrees with the hypothesis that the emission is the result of electron plasma wave emission.

  19. Bistable Intrinsic Charge Fluctuations of a Dust Grain Subject to Secondary Electron Emission in a Plasma

    CERN Document Server

    Shotorban, Babak

    2015-01-01

    A master equation was formulated to study intrinsic charge fluctuations of a grain in a plasma as ions and primary electrons are attached to the grain through collisional collection, and secondary electrons are emitted from the grain. Two different plasmas with Maxwellian and non-Maxwellian distributions were considered. The fluctuations could be bistable in either plasma when the secondary electron emission is present, as two stable macrostates, associated with two stable roots of the charge net current, may exist. Metastablity of fluctuations, manifested by the passage of the grain charge between two macrostates, was shown to be possible.

  20. Bistable intrinsic charge fluctuations of a dust grain subject to secondary electron emission in a plasma.

    Science.gov (United States)

    Shotorban, B

    2015-10-01

    A master equation was formulated to study intrinsic charge fluctuations of a grain in a plasma as ions and primary electrons are attached to the grain through collisional collection, and secondary electrons are emitted from the grain. Two different plasmas with Maxwellian and non-Maxwellian distributions were considered. The fluctuations could be bistable in either plasma when the secondary electron emission is present, as two stable macrostates, associated with two stable roots of the charge net current, may exist. Metastablity of fluctuations, manifested by the passage of the grain charge between two macrostates, was shown to be possible.

  1. Radio rebrightening of the GRB afterglow by the accompanying supernova

    CERN Document Server

    Duran, Rodolfo Barniol

    2015-01-01

    The gamma-ray burst (GRB) jet powers the afterglow emission by shocking the surrounding medium, and radio afterglow can now be routinely observed to almost a year after the explosion. Long-duration GRBs are accompanied by supernovae (SNe) that typically contain much more energy than the GRB jet. Here we consider the fact that the SN blast wave will also produce its own afterglow, which will peak at much later time (since it is non-relativistic), when the SN blast wave transitions from a coasting phase to a decelerating Sedov-Taylor phase. We predict that this component will peak generally a few tens of years after the explosion and it will outshine the GRB powered afterglow well-before its peak emission. In the case of GRB 030329, where the external density is constrained by the $\\sim 10$-year coverage of the radio GRB afterglow, the radio emission is predicted to start rising over the next decade and to continue to increase for the following decades up to a level of $\\sim 0.5$ mJy. Detection of the SN-powere...

  2. The Detectability of Orphan Afterglows

    Science.gov (United States)

    Nakar, Ehud; Piran, Tsvi; Granot, Jonathan

    2002-11-01

    The realization that gamma-ray bursts (GRBs) release a constant amount of energy implies that post-jet-break afterglow evolution is largely universal. For a given redshift, all afterglows should be detected up to a fixed observer angle. We estimate the observed magnitude and the implied detectability of orphan afterglows. We show that for reasonable limiting magnitudes (mlim=25), orphan afterglows will typically be detected from small (~10°) angles away from the GRB jet axis. A detected orphan afterglow generally corresponds to a ``near miss'' of a GRB whose jet is pointing just slightly away from us. With our most optimistic parameters, we expect that 15 orphan afterglows will be recorded in the Sloan Digital Sky Survey, and 35 transients will be recorded in a dedicated 2 m class telescope operating full time for a year in an orphan afterglow search. The rate is smaller by a factor of 15 for our ``canonical'' parameters. We show that for a given facility, an optimal survey should be shallower, covering a larger area, rather than deeper. The limiting magnitude should not be, however, lower than ~23, as in this case, more transients from on-axis GRBs will be discovered than orphan afterglows. About 15% of the transients could be discovered with a second exposure of the same area provided that it follows after 3, 4, and 8 days for mlim=23, 25, and 27, respectively.

  3. THz Wave emission from the intrinsic Josephson junctions of high T{sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, H; Koyama, T [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Machida, M [CCSE, Japan Atomic Energy Agency, 6-9-3 Higashi-Ueno, Taito-ku, Tokyo 110-0015 (Japan); Kadowaki, K, E-mail: matumoto@ldp.phys.tohoku.ac.j, E-mail: tkoyama@imr.tohoku.ac.j, E-mail: machida.masahiko@jaea.go.j, E-mail: kadowaki@ims.tsukuba.ac.j [Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan)

    2009-03-01

    Relating to the recent observation of a THz wave emission from the intrinsic Josephson junction of Bi-2212, we investigate temporal and spatial behaviors of electromagnetic fields around the junctions by numerical simulation. We consider 1)xz-model, where junctions and leads are stacked in the z-direction with homogeneity in the y-direction, and 2)xy-model, where junctions have a rectangular shape in the xy-plane with homogeneity in the z-direction. The result of the xz-model shows that the emitted electromagnetic field has the spatial pattern similar to that of the dipole emission. The result of the xy-model shows that waves are emitted in the all directions of the xy-plane and the frequency of the oscillation is controlled by the shorter length and is given by the Josephson frequency. The voltage-dependence and the angle-dependence of the emitted power are also studied.

  4. Pixelated CdTe detectors to overcome intrinsic limitations of crystal based positron emission mammographs

    Science.gov (United States)

    De Lorenzo, G.; Chmeissani, M.; Uzun, D.; Kolstein, M.; Ozsahin, I.; Mikhaylova, E.; Arce, P.; Cañadas, M.; Ariño, G.; Calderón, Y.

    2013-01-01

    A positron emission mammograph (PEM) is an organ dedicated positron emission tomography (PET) scanner for breast cancer detection. State-of-the-art PEMs employing scintillating crystals as detection medium can provide metabolic images of the breast with significantly higher sensitivity and specificity with respect to standard whole body PET scanners. Over the past few years, crystal PEMs have dramatically increased their importance in the diagnosis and treatment of early stage breast cancer. Nevertheless, designs based on scintillators are characterized by an intrinsic deficiency of the depth of interaction (DOI) information from relatively thick crystals constraining the size of the smallest detectable tumor. This work shows how to overcome such intrinsic limitation by substituting scintillating crystals with pixelated CdTe detectors. The proposed novel design is developed within the Voxel Imaging PET (VIP) Pathfinder project and evaluated via Monte Carlo simulation. The volumetric spatial resolution of the VIP-PEM is expected to be up to 6 times better than standard commercial devices with a point spread function of 1 mm full width at half maximum (FWHM) in all directions. Pixelated CdTe detectors can also provide an energy resolution as low as 1.5% FWHM at 511 keV for a virtually pure signal with negligible contribution from scattered events.

  5. AGN are cooler than you think: the intrinsic far-IR emission from QSOs

    CERN Document Server

    Symeonidis, M; Page, M J; Pearson, C; Bendo, G; Seymour, N; Oliver, S J

    2016-01-01

    We present an intrinsic AGN SED extending from the optical to the submm, derived with a sample of unobscured, optically luminous (vLv(5100)>10^43.5 erg/s) QSOs at z 10^43.5 erg/s). We note that for our sample of luminous QSOs, the average AGN emission is at least as high as, and mostly higher than, the total stellar powered emission at all wavelengths from the optical to the submm. This implies that in many galaxies hosting powerful AGN, there is no `safe' broadband photometric observation (at lambda<1000um) which can be used in calculating star-formation rates without subtracting the AGN contribution. Roughly, the AGN contribution may be ignored only if the intrinsic AGN luminosity at 5100 Ang is at least a factor of 4 smaller than the total infrared luminosity (L_IR; 8-1000um) of the galaxy. Finally, we examine the implication of our work in statistical studies of star-formation in AGN host galaxies.

  6. $\\gamma$-Ray Burst Afterglow Polarization and Analytic Light Curves

    CERN Document Server

    Gruzinov, A V; Gruzinov, Andrei; Waxman, Eli

    1999-01-01

    GRB afterglow polarization is discussed. We find an observable, up to 10%, polarization, if the magnetic field coherence length grows at about the speed of light after the field is generated at the shock front. Detection of a polarized afterglow would show that collisionless ultrarelativistic shocks can generate strong large scale magnetic fields and confirm the synchrotron afterglow model. Non-detection, at a 1% level, would imply that either the synchrotron emission model is incorrect, or that strong magnetic fields, after they are generated in the shock, somehow manage to stay un-dissipated at ``microscopic'', skin depth, scales. Analytic lightcurves of synchrotron emission from an ultrarelativistic self-similar blast wave are obtained for an arbitrary electron distribution function, taking into account the effects of synchrotron cooling. The peak synchrotron flux and the flux at frequencies much smaller than the peak frequency are insensitive to the details of the electron distribution function; hence the...

  7. Intrinsic disc emission and the Soft X-ray Excess in AGN

    CERN Document Server

    Done, Chris; Jin, Chichuan; Blaes, Omer; Ward, Martin

    2011-01-01

    (Abridged) Narrow Line Seyfert 1 (NLS1) galaxies have low mass black holes and mass accretion rates close to (or exceeding) Eddington, so a standard blackbody accretion disc should peak in the EUV. However, the lack of true absorption opacity in the disc means that the emission is better approximated by a colour temperature corrected blackbody, and this colour temperature correction is large enough ($\\sim 2.4$) that the bare disc emission from a zero spin black hole can extend into the soft X-ray bandpass. Part of the soft X-ray excess seen in these objects must be intrinsic emission from the disc unless the vertical structure is very different to that predicted. However, the soft excess is much broader than predicted by a bare disc spectrum, indicating some Compton upscattering by cool, optically thick material. We associate this with the disc itself, so it must ultimately be powered by mass accretion. We build an energetically self consistent model assuming that the emission thermalises at large radii, but ...

  8. The rise of the afterglow in GRB 050820a

    CERN Document Server

    Genet, F; Mochkovitch, R

    2007-01-01

    The early optical afterglow of GRB 050820a recorded by the RAPTOR telescope shows both a contribution from the prompt emission and the initial rise of the afterglow. It is therefore well-suited for the study of the dynamical evolution of the GRB ejecta when it first undergoes the decelerating effect of the environment. This is a complex phase where the internal, reverse, and forward shocks can all be present simultaneously. We have developed a simplified model that can follow these different shocks in an approximate, but self-consistent way. It is applied to the case of GRB 050820a to obtain the prompt and afterglow light curves. We show that the rise of the afterglow during the course of the prompt emission has some important consequences. The reverse shock propagates back into the ejecta before internal shocks are completed, which affects the shape of the gamma-ray profile. We get the best results when the external medium has a uniform density, but obtaining a simultaneous fit of the prompt and afterglow em...

  9. Terahertz-wave emission from Bi2212 intrinsic Josephson junctions: a review on recent progress

    Science.gov (United States)

    Kakeya, Itsuhiro; Wang, Huabing

    2016-07-01

    Emission of terahertz (THz) electromagnetic (EM) waves from a high critical temperature (T c) superconductor intrinsic Josephson junction (IJJ) is a new and promising candidate for practical applications of superconducting devices. From the engineering viewpoint, the IJJ THz source is competitive against the present semiconducting THz sources such as quantum cascade lasers (QCLs) and resonance tunnelling diode oscillators because of its broad tunable frequency range and ease of the fabrication process for the device. The emitted EM waves are considered to be coherent because the emission is yielded by synchronisation of thousand stacked IJJs consisting of the mesa device. This synchronisation is peculiar: the resonant frequency of each IJJ is distributed because the cross section of the mesa device is trapezoidal in shape. One of the key features of the synchronisation mechanism is the temperature inhomogeneity of the emitting device. In this topical review, we describe the recent progress in studies of IJJ THz sources with particular emphasis on the relevance of the temperature inhomogeneity to the synchronisation and the emission intensity. This review is of specific interest because the IJJ THz source shows the rich variety of functions due to self-heating which has always been a detrimental feature in the present superconducting devices. Moreover, the thermal managements used for IJJ THz sources will be common with those of other semiconducting devices such as QCLs. In addition, this review is to invite the readers into related research through the detailed descriptions of experimental procedures.

  10. Rising optical afterglows seen by TAROT

    CERN Document Server

    Gendre, B; Stratta, G; Preger, B; Piro, L; Pelangeon, A; Galli, A; Cutini, S; Corsi, A; Boër, M; Atteia, J L

    2008-01-01

    We present the multi-wavelength study of those gamma-ray bursts observed by TAROT. These events are characterized by the presence at early time of a rising in their optical light curves lasting a few hundred of seconds. In one case (GRB 060904B), a flare occurs at similar time in the X-ray band, while in the other cases the X-ray light curves appear smooth during the optical rise. We investigate the possible nature of this behavior and conclude th at a multi-component emission is mandatory to explain the optical-to-X-ray afterglow.

  11. RAPTOR observations of the early optical afterglow from GRB 050319

    CERN Document Server

    Wozniak, P R; Wren, J A; White, R R; Evans, S M; Casperson, D

    2005-01-01

    The RAPid Telescopes for Optical Response (RAPTOR) system at Los Alamos National Laboratory observed GRB 050319 starting 25.4 seconds after gamma-ray emission triggered the Burst Alert Telescope (BAT) on-board the Swift satellite. Our well sampled light curve of the early optical afterglow is composed of 32 points (derived from 70 exposures) that measure the flux decay during the first hour after the GRB. The GRB 050319 light curve measured by RAPTOR can be described as a relatively gradual flux decline (power-law index alpha = -0.37) with a transition, at about 400 s after the GRB, to a faster flux decay (alpha = -0.91). The addition of other available measurements to the RAPTOR light curve suggests that another emission component emerged after 10^4 s. We hypothesize that the early afterglow emission is powered by extended energy injection or delayed reverse shock emission followed by the emergence of forward shock emission.

  12. Green chemistry-mediated synthesis of nanostructures of afterglow phosphor

    Science.gov (United States)

    Sharma, Pooja; Haranath, D.; Chander, Harish; Singh, Sukhvir

    2008-04-01

    Various nanostructures of SrAl 2O 4:Eu 2+, Dy 3+ (SAC) afterglow phosphor were prepared in a single-step reaction using a green chemistry-mediated modified combustion process. The evolution of hazardous NxOx gases during the customary combustion reaction was completely eliminated by employing an innovative complex formation route. Another fascinating feature of the process was that, a slight change in the processing conditions ensured the synthesis of either nanoparticles or nanowires. The photoluminescence spectrum of nanophosphor showed a slight blue shift in emission (˜511 nm) as compared to the bulk phosphor (˜520 nm). The afterglow (decay) profiles of SAC nanoparticles, nanowires and bulk phosphor were compared. The chemistry underlying the nanostructure synthesis and the probable afterglow mechanism were discussed.

  13. Gamma-ray bursts afterglows in magnetized stellar winds

    CERN Document Server

    Lemoine, Martin

    2011-01-01

    Recent analytical and numerical work have converged to argue that the successful development of relativistic Fermi acceleration requires a weak magnetization of the unshocked plasma, all the more so at high Lorentz factors. The present paper proposes to test this conclusion by computing the afterglow of a gamma-ray burst outflow propagating in a magnetized stellar wind using "ab initio" principles regarding the microphysics of relativistic Fermi acceleration. It is shown that in such magnetized environments, one expects a drop-out in the X-ray band on sub-day scales due to the concomitant inhibition of Fermi acceleration and redshifting of the synchrotron emission of shock heated electrons. At later times, Fermi acceleration becomes operative when the blast Lorentz factor drops below a certain critical value, leading to the recovery of the standard afterglow light curve. Interestingly, the observed drop-out bears resemblance with the fast decay found in gamma-ray bursts early X-ray afterglows.

  14. On the anomalous afterglow seen in a chameleon afterglow search

    CERN Document Server

    Steffen, Jason H; Baumbaugh, Alan; Chou, Aaron S; Tomlin, Ray

    2012-01-01

    We present data from our investigation of the anomalous orange-colored afterglow that was seen in the GammeV Chameleon Afterglow Search (CHASE). These data includes information about the broad band color of the observed glow, the relationship between the glow and the temperature of the apparatus, and other data taken prior to and during the science operations of CHASE. While differing in several details, the generic properties of the afterglow from CHASE are similar to luminescence seen in some vacuum compounds. Contamination from this, or similar, luminescent signatures will likely impact the design of implementation of future experiments involving single photon detectors and high intensity light sources in a cryogenic environment.

  15. The Ultra-long GRB 111209A. II. Prompt to Afterglow and Afterglow Properties

    Science.gov (United States)

    Stratta, G.; Gendre, B.; Atteia, J. L.; Boër, M.; Coward, D. M.; De Pasquale, M.; Howell, E.; Klotz, A.; Oates, S.; Piro, L.

    2013-12-01

    The "ultra-long" gamma-ray burst GRB 111209A at redshift z = 0.677 is the longest GRB ever observed thus far, with a rest frame prompt emission duration of ~4 hr. In order to explain the burst exceptional longevity, a low-metallicity blue supergiant progenitor was invoked. In this article we further constrain the phenomenology and progenitor properties of this peculiar GRB by performing a multiband temporal and spectral analysis of both the prompt and the afterglow emission. We use proprietary and publicly available data from Swift, Konus WIND, XMM-Newton, and TAROT, as well as from other ground-based optical and radio telescopes. We find some peculiar properties that are possibly connected to the exceptional nature of this burst, namely: (1) an unprecedented large optical delay of 410 ± 50 s between the peak time in gamma-rays and the peak time in the optical of a marked multiwavelength flare; (2) multiwavelength prompt emission spectral modeling requires a certain amount of dust in the circumburst environment. The dust produces a rest frame visual extinction of AV = 0.3-1.5 mag, and may undergo destruction at late times; and (3) we detect the presence of a hard spectral extra power-law component at the end of the X-ray steep steep decay phase and before the start of the X-ray afterglow, which has never been revealed thus far in past GRBs. The optical afterglow shows more usual properties; it has a flux power-law decay with an index of 1.6 ± 0.1 and a late rebrightening feature observed at ~1.1 the day after the first Burst Alert Telescope trigger. We discuss our findings in the context of several possible interpretations that have been given thus far of the complex multiband GRB phenomenology and propose a binary channel formation for the blue supergiant progenitor.

  16. The ultra-long GRB 111209A. II. Prompt to afterglow and afterglow properties

    Energy Technology Data Exchange (ETDEWEB)

    Stratta, G. [Osservatorio Astronomico di Roma (OAR/INAF), via Frascati 33, I-00040 Monte Porzio Catone (Italy); Gendre, B.; Boër, M. [ARTEMIS, UMR 7250 (CNRS/OCA/UNS), boulevard de l' Observatoire, BP 4229, F-06304 Nice Cedex (France); Atteia, J. L. [Université de Toulouse, UPS-OMP, IRAP, F-31400 Toulouse (France); Coward, D. M.; Howell, E. [School of Physics, University of Western Australia (UWA), Crawley, WA 6009 (Australia); De Pasquale, M.; Oates, S. [Mullard Space Science Laboratory (MSSL), University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT (United Kingdom); Klotz, A. [IRAP, 14, avenue Edouard Belin, F-31400 Toulouse (France); Piro, L. [Istituto di Astrofisica e Planetologia Spaziali di Roma (IAPS/INAF), via fosso del cavaliere 100, I-00133 Roma (Italy)

    2013-12-10

    The 'ultra-long' gamma-ray burst GRB 111209A at redshift z = 0.677 is the longest GRB ever observed thus far, with a rest frame prompt emission duration of ∼4 hr. In order to explain the burst exceptional longevity, a low-metallicity blue supergiant progenitor was invoked. In this article we further constrain the phenomenology and progenitor properties of this peculiar GRB by performing a multiband temporal and spectral analysis of both the prompt and the afterglow emission. We use proprietary and publicly available data from Swift, Konus WIND, XMM-Newton, and TAROT, as well as from other ground-based optical and radio telescopes. We find some peculiar properties that are possibly connected to the exceptional nature of this burst, namely: (1) an unprecedented large optical delay of 410 ± 50 s between the peak time in gamma-rays and the peak time in the optical of a marked multiwavelength flare; (2) multiwavelength prompt emission spectral modeling requires a certain amount of dust in the circumburst environment. The dust produces a rest frame visual extinction of A{sub V} = 0.3-1.5 mag, and may undergo destruction at late times; and (3) we detect the presence of a hard spectral extra power-law component at the end of the X-ray steep steep decay phase and before the start of the X-ray afterglow, which has never been revealed thus far in past GRBs. The optical afterglow shows more usual properties; it has a flux power-law decay with an index of 1.6 ± 0.1 and a late rebrightening feature observed at ∼1.1 the day after the first Burst Alert Telescope trigger. We discuss our findings in the context of several possible interpretations that have been given thus far of the complex multiband GRB phenomenology and propose a binary channel formation for the blue supergiant progenitor.

  17. Testing an unifying view of GRB afterglows

    CERN Document Server

    Nardini, M; Ghirlanda, G; Celotti, A

    2009-01-01

    Four years after the launch the Swift satellite the nature of the GRBs broadband afterglow behaviour is still an open issue. The standard external shock fireball model cannot easily explain the combined temporal and spectral properties of Optical to X-ray afterglows. We analysed the rest frame de-absorbed and K-corrected Optical and X-ray light curves of a sample of 33 GRBs with known redshift and optical extinction at the host frame. We modelled their broadband behaviour as the sum of the standard forward shock emission due to the interaction of a fireball with the circum-burst medium and an additional component. This description provides a good agreement with the observed light curves despite their complexity and diversity and can also account for the lack of achromatic late times jet breaks and the presence of chromatic breaks in several GRBs lightcurves. In order to test the predictions of such modelling we analysed the X-ray time resolved spectra searching for possible spectral breaks within the observed...

  18. Extinction and Absorption of the Afterglow of GRB980329

    CERN Document Server

    Reichart, D E; Metzger, M R; Quashnock, J M; Cole, D M; Castander, F J; Cooray, A R; Vanden Berk, Daniel E; Reichart, Daniel E.; Lamb, Donald Q.; Metzger, Mark R.; Quashnock, Jean M.; Cole, David M.; Castander, Francisco J.; Cooray, Asantha R.; Berk, Daniel E. Vanden

    1998-01-01

    We report R-, J- and K-band observations of the GRB980329 field made on April 1 with the APO 3.5-m telescope, and J- and K-band observations made between April 6 - 8 with the Keck-I 10-m telescope. We show that these data and other reported measurements are consistent with a power-law fading of the optical/NIR source that is coincident with the variable radio source VLA J0702+3850. This establishes this source as the afterglow of GRB980329. We construct a model of the observed optical/NIR and X-ray spectrum of burst afterglows that takes into account the extinction of optical/NIR light and the absorption of soft X rays by dust and gas along the line-of-sight to the burst and in any host galaxy. For GRB980329, we find a rest-frame V-band absorption magnitude of A_V(1+z) = 3.00 +/- 0.25 mag, assuming a power law for the intrinsic spectrum, and that the observed spectrum of the burst afterglow is fully consistent with extinction of the intrinsic spectrum in the optical/NIR. This value of A_V is too large to be c...

  19. Investigation of intrinsic and extrinsic defects effective role on producing intense red emission in ZnO:Eu nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Najafi, Mehrdad, E-mail: najafi@shahroodut.ac.ir; Haratizadeh, Hamid

    2015-05-15

    Highlights: • Effective role of defects on producing red emission at indirect excitation. • V{sub Zn} and V{sub O} defects have important role on energy transfer. • Mg related defects and Zn{sub i} defects were responsible for blue emission. • Extrinsic and intrinsic defects mediated energy transfer to sensitize Eu{sup 3+} ions. • Decrease of red emission because of diminishing in oxygen vacancy. - Abstract: Europium doped ZnO nanorads and nanosheets were synthesized by hydrothermal method. Effects of Mg doping, morphology and annealing in oxygen ambient on structural and optical properties of ZnO nanostructures were investigated using X-ray diffraction (XRD), particle size analysis (PSA), thermo gravimetric analysis (TGA), differential thermal analysis (DTA), differential thermo gravimetry (DTG), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). This study recommends that both of intrinsic and extrinsic defects facilitate energy transfer (ET) from the ZnO host to Eu{sup 3+} ions and consequently have efficient role on producing intense red emission at indirect excitation. The results also showed that annealing process improved the crystal structure of ZnO nanosheets due to decrease of surface defects; however decreased ET and red emission because of diminishing in oxygen vacancy. In addition in ZnO nanorods sample with more surface area in comparison with ZnO nanosheets sample deep level emissions are enhanced.

  20. On associating Fast Radio Bursts with afterglows

    CERN Document Server

    Vedantham, H K; Mooley, K; Frail, D; Hallinan, G; Kulkarni, S R

    2016-01-01

    A radio source that faded over 6 days, with a redshift $z\\approx0.5$ host, has been identified by Keane et al. (2016) as the transient afterglow to a Fast Radio Burst (FRB 150418). We report follow-up radio and optical observations of the afterglow candidate, and find a source that is consistent with an active galactic nucleus (AGN). If the afterglow-candidate is nonetheless a prototypical FRB afterglow, existing surveys limit the fraction of FRBs that produce afterglows to 0.25 for modulation-index $m=\\Delta S/\\bar{S}\\geq0.7$, and 0.07 for $m\\geq1$, at 95\\% confidence. Afterglow associations with the barrage of bursts expected from future FRB surveys must satisfy constraints on the afterglow rate set by state of the art slow-transient surveys.

  1. Afterglow processes responsible for memory effect in nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Pejovic, M. M. [Faculty of Electronic Engineering, University of Nis, Aleksandra Medvedeva 14, Nis (Serbia); Center of Scientific Research of the Serbian Academy of Sciences and Arts, University of Nis, Univerzitetski trg 2, Nis (Serbia); Nesic, N. T.; Pejovic, M. M.; Zivanovic, E. N. [Faculty of Electronic Engineering, University of Nis, Aleksandra Medvedeva 14, Nis (Serbia)

    2012-07-01

    The mechanisms responsible for memory effect in nitrogen at 6.6 mbars have been analysed based on experimental data of electrical breakdown time delay as a function of afterglow period. The analysis has shown that positive ions remaining from previous discharge, as well as metastable and highly vibrationally excited molecules, are responsible for memory effect in the early afterglow. These molecules lead to the formation of positive ions in mutual collisions in the afterglow. Positive ions initiate secondary electron emission from the cathode of a nitrogen-filled tube when voltage higher than static breakdown voltage is applied on the electrodes. On the other hand, N({sup 4}S) atoms have a large influence on memory effect in late afterglow. They recombine on the cathode surface forming metastable molecules, which release secondary electrons in collision with the cathode. The higher values of electrical breakdown time delay in the case of the tube with borosilicate glass walls than in the case of the tube with copper walls are a consequence of faster de-excitation of neutral active particles on the glass. Indirect confirmation of this assumption has been obtained when the tubes were irradiated with gamma radiation.

  2. The Supercritical Pile GRB Model: The Prompt to Afterglow Evolution

    Science.gov (United States)

    Mastichiadis, A.; Kazanas, D.

    2009-01-01

    The "Supercritical Pile" is a very economical GRB model that provides for the efficient conversion of the energy stored in the protons of a Relativistic Blast Wave (RBW) into radiation and at the same time produces - in the prompt GRB phase, even in the absence of any particle acceleration - a spectral peak at energy approx. 1 MeV. We extend this model to include the evolution of the RBW Lorentz factor Gamma and thus follow its spectral and temporal features into the early GRB afterglow stage. One of the novel features of the present treatment is the inclusion of the feedback of the GRB produced radiation on the evolution of Gamma with radius. This feedback and the presence of kinematic and dynamic thresholds in the model can be the sources of rich time evolution which we have began to explore. In particular. one can this may obtain afterglow light curves with steep decays followed by the more conventional flatter afterglow slopes, while at the same time preserving the desirable features of the model, i.e. the well defined relativistic electron source and radiative processes that produce the proper peak in the (nu)F(sub nu), spectra. In this note we present the results of a specific set of parameters of this model with emphasis on the multiwavelength prompt emission and transition to the early afterglow.

  3. Intrinsic single-band upconversion emission in colloidal Yb/Er(Tm):Na3Zr(Hf)F7 nanocrystals.

    Science.gov (United States)

    Chen, Daqin; Lei, Lei; Zhang, Rui; Yang, Anping; Xu, Ju; Wang, Yuansheng

    2012-11-07

    Novel Yb/Er(Tm):Na(3)MF(7) (M = Zr, Hf) nanocrystals with intrinsic single-band upconversion emission, in contrast to the routine lanthanide-doped fluoride nanocrystals which show typical multi-band upconversion emissions, are reported for the first time. Specifically, the red upconversion intensity of the Yb/Er:Na(3)ZrF(7) nanocrystals is about 5 times as high as that of the hexagonal Yb/Er:NaYF(4) ones with a similar crystal size.

  4. Weak Hard X-ray Emission from Broad Absorption Line Quasars: Evidence for Intrinsic X-ray Weakness

    CERN Document Server

    Luo, B; Alexander, D M; Stern, D; Teng, S H; Arévalo, P; Bauer, F E; Boggs, S E; Christensen, F E; Comastri, A; Craig, W W; Farrah, D; Gandhi, P; Hailey, C J; Harrison, F A; Koss, M; Ogle, P; Puccetti, S; Saez, C; Scott, A E; Walton, D J; Zhang, W W

    2014-01-01

    We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z=0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z330 times weaker than expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with 33%) of intrinsically X-ray weak objects among the BAL quasars with significantly weak <10 keV emission. We suggest that intrinsically X-ray weak quasars might be preferentially observed as BAL quasars.

  5. Hydrodynamic Evolution of GRB Afterglow

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We investigate the dynamics of a relativistic fireball which decelerates as it sweeps up ambient matter. Not only the radiative and adiabatic cases, but also the realistic intermediate cases are calculated. We perform numerical calcula-tion for various ambient media and sizes of beaming expansion, and find that the deceleration radius R0 may play an important role for the hydrodynamic evolution of GRB afterglow.

  6. The weak INTEGRAL bursts GRB040223 and GRB040624: an emerging population of dark afterglows

    CERN Document Server

    Filliatre, P; D'Avanzo, P; De Luca, A; Gotz, D; McGlynn, S; McBreen, S; Fugazza, D; Antonelli, A; Campana, S; Chincarini, G; Cucchiara, A; Valle, M D; Foley, S; Goldoni, P; Hanlon, L; Israel, G; McBreen, B; Mereghetti, S; Stella, L; Tagliaferri, G

    2005-01-01

    We report here gamma-ray, X-ray and near-infrared observations of GRB040223 along with gamma-ray and optical observations of GRB040624. GRB040223 was detected by INTEGRAL close to the Galactic plane and GRB040624 at high Galactic latitude. Analyses of the prompt emission detected by the IBIS instrument on INTEGRAL are presented for both bursts. The two GRBs have long durations, slow pulses and are weak. The gamma-ray spectra of both bursts are best fit with steep power-laws, implying they are X-ray rich. GRB040223 is among the weakest and longest of INTEGRAL GRBs. The X-ray afterglow of this burst was detected 10 hours after the prompt event by XMM-Newton. The measured spectral properties are consistent with a column density much higher than that expected from the Galaxy, indicating strong intrinsic absorption. We carried out near-infrared observations 17 hours after the burst with the NTT of ESO, which yielded upper limits. Given the intrinsic absorption, we find that these limits are compatible with a simpl...

  7. Radio Afterglows and Host Galaxies of Gamma-Ray Bursts

    CERN Document Server

    Li, Long-Biao; Huang, Yong-Feng; Wu, Xue-Feng; Kong, Si-Wei; Li, Di; Chang, Heon-Young; Choi, Chul-Sung

    2015-01-01

    Considering the contribution of the emission from the host galaxies of gamma-ray bursts (GRBs) to the radio afterglows, we investigate the effect of host galaxies on observations statistically. For the three types of events, e.g. low-luminosity, standard and high-luminosity GRBs, it is found that a tight correlation exists between the ratio of the radio flux (RRF) of host galaxy to the total radio peak emission and the observational frequency. Especially, toward lower frequencies, the contribution from the host increases significantly. The correlation can be used to get a useful estimate for the radio brightness of those host galaxies which only have very limited radio afterglow data. Using this prediction, we re-considered the theoretical radio afterglow light curves for four kinds of events, i.e. high-luminosity, low-luminosity, standard and failed GRBs, taking into account the contribution from the host galaxies and aiming at exploring the detectability of these events by the Five-hundred-meter Aperture Sp...

  8. Afterglow kinetics and storage mechanism in CaF{sub 2}:Mn (TLD-400)

    Energy Technology Data Exchange (ETDEWEB)

    Danilkin, M. [Faculty of Physics and Chemistry, University of Tartu, Taehe 4, 51010 Tartu (Estonia)], E-mail: danilkin@ut.ee; Lust, A.; Ratas, A.; Seeman, V.; Kerikmaee, M. [Faculty of Physics and Chemistry, University of Tartu, Taehe 4, 51010 Tartu (Estonia)

    2008-02-15

    Thermoluminescence (TL) of CaF{sub 2}:Mn and the isothermal afterglow curves were studied after a pre-annealing of irradiated samples. Afterglow kinetics can be easily approximated with two exponents. A simple kinetic model is suggested. The TL main peak activation energy (1.597 eV) is very close to the dissociation energy of F{sub 2} molecule (1.606 eV) and exceeds the thermal decay activation energies of all the other intrinsic defects previously known in CaF{sub 2}. A mechanism of energy storage and release is discussed.

  9. Room-temperature single-photon emission from zinc oxide nanoparticle defects and their in vitro photostable intrinsic fluorescence

    Directory of Open Access Journals (Sweden)

    Chung Kelvin

    2017-01-01

    Full Text Available Zinc oxide (ZnO is a promising semiconductor that is suitable for bioimaging applications due to its intrinsic defect fluorescence. However, ZnO generally suffers from poor photostability. We report room-temperature single-photon emission from optical defects found in ZnO nanoparticles (NPs formed by ion implantation followed by thermal oxidation in a silica substrate. We conduct a thorough investigation into the photophysics of a particularly bright defect and identify other single emitters within the NPs. Photostability was observed when the NPs were removed from the growth substrate and taken up by skin cells for in vitro imaging.

  10. Room-temperature single-photon emission from zinc oxide nanoparticle defects and their in vitro photostable intrinsic fluorescence

    Science.gov (United States)

    Chung, Kelvin; Karle, Timothy J.; Khalid, Asma; Abraham, Amanda N.; Shukla, Ravi; Gibson, Brant C.; Simpson, David A.; Djurišic, Aleksandra B.; Amekura, Hiroshi; Tomljenovic-Hanic, Snjezana

    2017-01-01

    Zinc oxide (ZnO) is a promising semiconductor that is suitable for bioimaging applications due to its intrinsic defect fluorescence. However, ZnO generally suffers from poor photostability. We report room-temperature single-photon emission from optical defects found in ZnO nanoparticles (NPs) formed by ion implantation followed by thermal oxidation in a silica substrate. We conduct a thorough investigation into the photophysics of a particularly bright defect and identify other single emitters within the NPs. Photostability was observed when the NPs were removed from the growth substrate and taken up by skin cells for in vitro imaging.

  11. GRB 110715A: the peculiar multiwavelength evolution of the first afterglow detected by ALMA

    Science.gov (United States)

    Sánchez-Ramírez, R.; Hancock, P. J.; Jóhannesson, G.; Murphy, Tara; de Ugarte Postigo, A.; Gorosabel, J.; Kann, D. A.; Krühler, T.; Oates, S. R.; Japelj, J.; Thöne, C. C.; Lundgren, A.; Perley, D. A.; Malesani, D.; de Gregorio Monsalvo, I.; Castro-Tirado, A. J.; D'Elia, V.; Fynbo, J. P. U.; Garcia-Appadoo, D.; Goldoni, P.; Greiner, J.; Hu, Y.-D.; Jelínek, M.; Jeong, S.; Kamble, A.; Klose, S.; Kuin, N. P. M.; Llorente, A.; Martín, S.; Nicuesa Guelbenzu, A.; Rossi, A.; Schady, P.; Sparre, M.; Sudilovsky, V.; Tello, J. C.; Updike, A.; Wiersema, K.; Zhang, B.-B.

    2017-02-01

    We present the extensive follow-up campaign on the afterglow of GRB 110715A at 17 different wavelengths, from X-ray to radio bands, starting 81 s after the burst and extending up to 74 d later. We performed for the first time a GRB afterglow observation with the ALMA observatory. We find that the afterglow of GRB 110715A is very bright at optical and radio wavelengths. We use the optical and near-infrared spectroscopy to provide further information about the progenitor's environment and its host galaxy. The spectrum shows weak absorption features at a redshift z = 0.8225, which reveal a host-galaxy environment with low ionization, column density, and dynamical activity. Late deep imaging shows a very faint galaxy, consistent with the spectroscopic results. The broad-band afterglow emission is modelled with synchrotron radiation using a numerical algorithm and we determine the best-fitting parameters using Bayesian inference in order to constrain the physical parameters of the jet and the medium in which the relativistic shock propagates. We fitted our data with a variety of models, including different density profiles and energy injections. Although the general behaviour can be roughly described by these models, none of them are able to fully explain all data points simultaneously. GRB 110715A shows the complexity of reproducing extensive multiwavelength broad-band afterglow observations, and the need of good sampling in wavelength and time and more complex models to accurately constrain the physics of GRB afterglows.

  12. Simulation Study Of Early Afterglows Observed With Swift

    Science.gov (United States)

    Nishikawa, Ken-Ichi; Hededal, C.; Hardee, P.; Mizuno, Y.; Fishman, G. J.

    2006-09-01

    A 3-D relativistic particle-in-cell code has been used to simulate the dynamics of forward and reverse shocks with thin and thick shells within the parameter constraints provided by present Swift observations and the present models of GRB emission. Our 3-D RPIC simulations have provided the dynamics of collisionless shocks in electron-ion and electron-positron plasmas with and without initial ambient magnetic fields and revealed the importance of ``jitter radiation'' with prompt and afterglow spectra due to the inhomogeneous magnetic fields generated by the Weibel instability. It is different from synchrotron radiation, which is usually assumed to be the dominant radiation process. We have investigated gamma-ray burst emissions from prompt, early, and late afterglows considering microscopic processes. Based on our previous investigation of the Weibel instability for each stage of evolution of ejecta propagating in the ISM, we have incorporated the plasma conditions (relativistic jets) with the density and composition of the plasmas, the magnetic field strength ($\\sigma$-values (the ratio of the electromagnetic energy flux to the particle energy flux)) and its direction, and the Lorentz factor for the different stages in prompt and afterglows. Systematic simulation studies of the relativistic collisionless shocks, associated particle acceleration, magnetic field generation and self-consistent radiation provide insight into undetermined issues in prompt and afterglows observed by Swift. Self-consistently calculated lightcurves, spectra, spectral evolutions, and polarization as function of viewing angle will be done to light a shed on recent new observations by Swift, in particular, X-ray flares, early steep decay, and shallow decay.

  13. Afterglow Observations Shed New Light on the Nature of X-ray Flashes

    CERN Document Server

    Granot, J; Perna, R; Granot, Jonathan; Ramirez-Ruiz, Enrico; Perna, Rosalba

    2005-01-01

    X-ray flashes (XRFs) and X-ray rich gamma-ray bursts (XRGRBs) share many observational characteristics with long duration GRBs, but the reason for which their prompt emission peaks at lower photon energies, $E_p$, is still under debate. Although many different models have been invoked in order to explain the lower $E_p$ values, their implications for the afterglow emission were not considered in most cases, mainly because observations of XRF afterglows have become available only recently. Here we examine the predictions of the various XRF models for the afterglow emission, and test them against the observations of XRF 030723 and XRGRB 041006, the events with the best monitored afterglow light curves in their respective class. We show that most existing XRF models are hard to reconcile with the observed afterglow light curves, which are very flat at early times. Such light curves are, however, naturally produced by a roughly uniform jet with relatively sharp edges that is viewed off-axis (i.e. from outside of ...

  14. Spectroscopy of a \\kappa-Cygnid fireball afterglow

    CERN Document Server

    Madiedo, José M

    2015-01-01

    A bright fireball with an absolute magnitude of -10.5 $\\pm$ 0.5 was recorded over the South of Spain on August 15, 2012. The atmospheric trajectory, radiant and heliocentric orbit of this event are calculated. These data show that the parent meteoroid belonged to the \\kappa-Cygnid meteoroid stream. The emission spectrum of this bolide, which was obtained in the wavelength range between 350 and 800 nm, suggests a chondritic nature for the progenitor meteoroid. Besides, the spectrum of the meteoric afterglow was also recorded for about 0.7 seconds. The evolution with time of the intensity of the main emission lines identified in this signal is discussed.

  15. A Characteristic Wind Signature in Prompt GRB Afterglows

    CERN Document Server

    Kobayashi, S; Zhang, B; Kobayashi, Shiho; Meszaros, Peter; Zhang, Bing

    2004-01-01

    We discuss the self-absorption effects in the prompt emission from the reverse shock in GRB afterglows that occur in the wind environment of a massive stellar progenitor. We point out that the higher self-absorption frequency in a wind environment implies a hump in the reverse shock emission spectrum and a more complex optical/IR light curve behavior than previously thought. We discuss a possible new diagnostic to test for the presence of a wind environment, and to provide constraints on the progenitor wind mass loss and the burst parameters.

  16. Weak hard X-ray emission from broad absorption line quasars: evidence for intrinsic X-ray weakness

    Energy Technology Data Exchange (ETDEWEB)

    Luo, B.; Brandt, W. N.; Scott, A. E. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Alexander, D. M.; Gandhi, P. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Teng, S. H. [Observational Cosmology Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Arévalo, P.; Bauer, F. E. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, 306, Santiago 22 (Chile); Boggs, S. E.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, F. E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Comastri, A. [INAF—Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Harrison, F. A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Koss, M. [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Ogle, P. [IPAC, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States); Puccetti, S. [ASDC—ASI, Via del Politecnico, I-00133 Roma (Italy); Saez, C. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); and others

    2014-10-10

    We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z < 1.3. However, their rest-frame ≈2 keV luminosities are 14 to >330 times weaker than expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three are not detected. The hard X-ray (8-24 keV) weakness observed by NuSTAR requires Compton-thick absorption if these objects have nominal underlying X-ray emission. However, a soft stacked effective photon index (Γ{sub eff} ≈ 1.8) for this sample disfavors Compton-thick absorption in general. The uniform hard X-ray weakness observed by NuSTAR for this and the pilot samples selected with <10 keV weakness also suggests that the X-ray weakness is intrinsic in at least some of the targets. We conclude that the NuSTAR observations have likely discovered a significant population (≳ 33%) of intrinsically X-ray weak objects among the BAL quasars with significantly weak <10 keV emission. We suggest that intrinsically X-ray weak quasars might be preferentially observed as BAL quasars.

  17. Reddening, Emission-Line, and Intrinsic Absorption Properties in the Narrow-Line Seyfert 1 Galaxy Akn 564

    CERN Document Server

    Crenshaw, D M; Turner, T J; Collier, S J; Peterson, B M; Brandt, W N; Clavel, J; George, I M; Horne, K; Kriss, G A; Mathur, S; Netzer, H; Pogge, R W; Pounds, K A; Romano, P; Shemmer, O; Wamsteker, W

    2002-01-01

    We use Hubble Space Telescope UV and optical spectra of the narrow-line Seyfert 1 (NLS1) galaxy Akn 564 to investigate its internal reddening and properties of its emission-line and intrinsic UV absorption gas. We find that the extinction curve of Akn 564, derived from a comparison of its UV/optical continuum to that of an unreddened NLS1, lacks a 2200 A bump and turns up towards the UV at a longer wavelength (4000 A) than the standard Galactic, LMC, and SMC curves. However, it does not show the extremely steep rise to 1200 A that characterizes the extinction curve of the Seyfert 1 galaxy NGC 3227. The emission-lines and continuum experience the same amount of reddening, indicating the presence of a dust screen that is external to the narrow-line region (NLR). Echelle spectra from the Space Telescope Imaging Spectrograph show intrinsic UV absorption lines due to Ly-alpha, N V, C IV, Si IV, and Si III, centered at a radial velocity of -190 km/s (relative to the host galaxy). Photoionization models of the UV ab...

  18. MAGIC observation of the GRB080430 afterglow

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Backes, M; Baixeras, C; Balestra, S; Barrio, J A; Bastieri, D; González, J Becerra; Becker, J K; Bednarek, W; Berdyugin, A; Berger, K; Bernardini, E; Biland, A; Bock, R K; Bonnoli, G; Bordas, P; Tridon, D Borla; Bosch-Ramon, V; Bose, D; Braun, I; Bretz, T; Britzger, D; Camara, M; Carmona, E; Carosi, A; Colin, P; Commichau, S; Contreras, J L; Cortina, J; Costado, M T; Covino, S; Dazzi, F; De Angelis, A; del Pozo, E de Cea; Reyes, R De los; De Lotto, B; De Maria, M; De Sabata, F; Mendez, C Delgado; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Elsaesser, D; Errando, M; Ferenc, D; Fernández, E; Firpo, R; Fonseca, M V; Font, L; Galante, N; López, R J García; Garczarczyk, M; Gaug, M; Godinovic, N; Goebel, F; Hadasch, D; Herrero, A; Hildebrand, D; Höhne-Mönch, D; Hose, J; Hrupec, D; Hsu, C C; Jogler, T; Klepser, S; Krähenbühl, T; Kranich, D; La Barbera, A; Laille, A; Leonardo, E; Lindfors, E; Lombardi, S; Longo, F; López, M; Lorenz, E; Majumdar, P; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Miyamoto, H; Moldón, J; Moles, M; Moralejo, A; Nieto, D; Nilsson, K; Ninkovic, J; Orito, R; Oya, I; Paoletti, R; Paredes, J M; Pasanen, M; Pascoli, D; Pauss, F; Pegna, R G; Perez-Torres, M A; Persic, M; Peruzzo, L; Prada, F; Prandini, E; Puchades, N; Puljak, I; Reichardt, I; Rhode, W; Ribó, M; Rico, J; Rissi, M; Rügamer, S; Saggion, A; Saito, T Y; Salvati, M; Sánchez-Conde, M; Satalecka, K; Scalzotto, V; Scapin, V; Schweizer, T; Shayduk, M; Shore, S N; Sierpowska-Bartosik, A; Sillanpää, A; Sitarek, J; Sobczynska, D; Spanier, F; Spiro, S; Stamerra, A; Steinke, B; Strah, N; Struebig, J C; Suric, T; Takalo, L; Tavecchio, F; Temnikov, P; Tescaro, D; Teshima, M; Torres, D F; Turini, N; Vankov, H; Wagner, R M; Zabalza, V; Zandanel, F; Zanin, R; Zapatero, J; de Ugarte-Postigo, A

    2015-01-01

    Context: Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of gamma-ray bursts during the prompt phase, i.e. the initial burst of high-energy radiation, and during the long-lasting afterglows. In spite of many successes in interpreting these phenomena, there are still several open key questions about the fundamental emission processes, their energetics and the environment. Aim: Independently of specific gamma-ray burst theoretical recipes, spectra in the GeV/TeV range are predicted to be remarkably simple, being satisfactorily modeled with power-laws, and therefore offer a very valuable tool to probe the extragalactic background light distribution. Furthermore, the simple detection of a component at very-high energies, i.e. at $\\sim 100$\\,GeV, would solve the ambiguity about the importance of various possible emission processes, which provide barely distinguishable scenarios at lower energies. Me...

  19. The Case for Anisotropic Afterglow Efficiency within Gamma-Ray Burst Jets

    CERN Document Server

    Eichler, D; Eichler, David; Granot, Jonathan

    2005-01-01

    Early X-ray afterglows recently detected by {\\it Swift} frequently show a phase of very shallow flux decay lasting from a few hundred seconds up to $\\sim 10^4 $s, followed by a steeper, more familiar decay. We suggest that the flat early part of the light curve may be a combination of the decaying tail of the prompt emission and the delayed onset of the afterglow emission observed from viewing angles slightly outside the edge of the jet, as predicted previously. This would imply that a significant fraction of viewers have a very small external shock energy along their line of sight and a very high $\\gamma $-ray to kinetic energy ratio. The early flat phase in the afterglow light curve implies, according to this or other interpretations, a very large $\\gamma $-ray efficiency, typically $\\gtrsim 90%$, which is very difficult to produce by internal shocks.

  20. The very red afterglow of GRB 000418: Further evidence for dust extinction in a gamma-ray burst host galaxy

    DEFF Research Database (Denmark)

    Klose, S.; Stecklum, B.; Masetti, N.;

    2000-01-01

    We report near-infrared and optical follow-up observations of the afterglow of the GRB 000418 starting 2.5 days after the occurrence of the burst and extending over nearly 7 weeks. GRB 000418 represents the second case for which the afterglow was initially identified by observations in the near-i......) bursts are associated with events in star-forming regions.......-infrared. During the first 10 days its R-band afterglow was well characterized by a single power-law decay with a slope of 0.86. However, at later times the temporal evolution of the afterglow flattens with respect to a simple power-law decay. Attributing this to an underlying host galaxy, we find its magnitude...... to be R = 23.9 and an intrinsic afterglow decay slope of 1.22. The afterglow was very red with R-K approximate to 4 mag. The observations can be explained by an adiabatic, spherical fireball solution and a heavy reddening due to dust extinction in the host galaxy. This supports the picture that (long...

  1. Gamma-Ray Bursts: The Afterglow Revolution

    Science.gov (United States)

    Galama, Titus J.; Sari, Re'em

    GRBs were discovered with the Vela satellites, whose main purpose was to verify compliance with the 1963 Limited Nuclear Test Ban Treaty. Since their discovery these events, which emit the bulk of their energy in the 0.1 - 1.0 MeV range, and whose durations span milliseconds to tens of minutes, posed one of the great unsolved problems in astrophysics. GRBs are formed in extreme relativistic outflows and provide important information about highly relativistic acceleration mechanisms. Until 1997, no counterparts (quiescent as well as transient) could be found and observations did not provide a direct measurement of their distance. The breakthrough came in early 1997, when the Wide Field Cameras aboard the Italian-Dutch BeppoSAX satellite allowed rapid and accurate localization of GRBs. Follow-up on these positions resulted in the discovery of X-ray, optical and radio afterglows. These observations revealed that GRBs come from 'cosmological' distances, and that they are by far the most luminous photon sources in the Universe, with peak luminosities in γ rays up to 1052 erg/s, and total energy budgets up to several times 1053-54 erg (for assumed isotropic emission). Evidence is accumulating, however, that GRB outflow is collimated in the form of jets and when corrected for the geometry of the outflow the energies of GRBs appear to cluster around 5 x 1050 ergs- very comparable to that of supernovae. GRBs are rare phenomena with an overall rate about 2000 times smaller than that of supernovae. Indirect evidence in the last several years shows that a fraction of GRBs may be related to a peculiar type of supernova explosions. Theoretical work has shown that these supernovae most likely mark the birth events of stellar mass black holes as the final products of the evolution of very massive stars. A fundamental question is whether there are also other processes that can drive such an engine, for example the coalescence of a double neutron-star system. Finally, the

  2. The afterglow, redshift and extreme energetics of the gamma-ray burst of 23 January 1999

    NARCIS (Netherlands)

    Kulkarni, [No Value; Djorgovski, SG; Odewahn, SC; Bloom, JS; Gal, RR; Koresko, CD; Harrison, FA; Lubin, LM; Armus, L; Sari, R; Illingworth, GD; Kelson, DD; Magee, DK; van Dokkum, PG; Frail, DA; Mulchaey, JS; Malkan, MA; McClean, IS; Teplitz, HI; Koerner, D; Kirkpatrick, D; Kobayashi, N; Yadigaroglu, IA; Halpern, J; Piran, T; Goodrich, RW; Chaffee, FH; Feroci, M; Costa, E

    1999-01-01

    Long-lived emission, known as afterglow, has now been detected from about a dozen gamma-ray bursts. Distance determinations place the bursts at cosmological distances, with redshifts,z, ranging from similar to 1 to 3, The energy required to produce these bright gamma-ray flashes is enormous: up to s

  3. The ultra-long GRB 111209A - II. Prompt to afterglow and afterglow properties

    CERN Document Server

    Stratta, G; Atteia, J L; Boër, M; Coward, D M; De Pasquale, M; Howell, E; Klotz, A; Oates, S; Piro, L

    2013-01-01

    The "ultra-long" Gamma Ray Burst GRB 111209A at redshift z=0.677, is so far the longest GRB ever observed, with rest frame prompt emission duration of ~4 hours. In order to explain the bursts exceptional longevity, a low metallicity blue supergiant progenitor has been invoked. In this work, we further investigate this peculiar burst by performing a multi-band temporal and spectral analysis of both the prompt and the afterglow emission. We use proprietary and publicly available data from Swift, Konus Wind, XMM-Newton, TAROT as well as from other ground based optical and radio telescopes. We find some peculiar properties that are possibly connected to the exceptional nature of this burst, namely: i) an unprecedented large optical delay of 410+/-50 s is measured between the peak epochs of a marked flare observed also in gamma-rays after about 2 ks from the first Swift/BAT trigger; ii) if the optical and X-ray/gamma-ray photons during the prompt emission share a common origin, as suggested by their similar tempor...

  4. Afterglow of a microwave microstrip plasma as an ion source for mass spectrometry

    Science.gov (United States)

    Pfeuffer, Kevin P.; White, Allen; Broekaert, José A. C.; Hieftje, Gary M.

    2015-01-01

    A microwave-induced plasma that was previously used for optical emission spectrometry has been repurposed as an afterglow ion source for mass spectrometry. This compact microwave discharge, termed the microstrip plasma (MSP), is operated at 20-50 W and 2.45 GHz in helium at a flow of 300 mL/min. The primary background ions present in the afterglow are ionized and protonated water clusters. An exponential dilution chamber was used to introduce volatile organic compounds into the MSP afterglow and yielded limits of detection in the 40 ppb to 7 ppm range (v/v). A hydride-generation system was also utilized for detection of volatile hydride-forming elements (arsenic, antimony, tin) in the afterglow and produced limits of detection in the 10-100 ppb range in solution. The MSP afterglow was found capable of desorption and ionization of analyte species directly from a solid substrate, suggesting its use as an ion source for ambient desorption/ionization mass spectrometry.

  5. The possible ubiquity of energy injection in Gamma-Ray Burst afterglows

    CERN Document Server

    Panaitescu, A

    2012-01-01

    Since its launch in 2004, the Swift satellite has monitored the X-ray afterglows of several hundred Gamma-Ray Bursts, and revealed that their X-ray light-curves are more complex than previously thought, exhibiting up to three power-law segments. Energy injection into the relativistic blast-wave energizing the burst ambient medium has been proposed most often to be the reason for the X-ray afterglow complexity. We examine 117 light-curve breaks of 98 Swift X-ray afterglows, selected for their high-quality monitoring and well-constrained flux decay rates. Thirty percent of afterglows have a break that can be an adiabatic jet-break, in the sense that there is one variant of the forward-shock emission from a collimated outflow model that can account for both the pre- and post-break flux power-law decay indices, given the measured X-ray spectral slope. If allowance is made for a steady energy injection into the forward-shock, then another 56 percent of X-ray afterglows have a light-curve break that can be explaine...

  6. Starburst-driven galactic winds - I. Energetics and intrinsic X-ray emission

    Science.gov (United States)

    Strickland, David K.; Stevens, Ian R.

    2000-05-01

    Starburst-driven galactic winds are responsible for the transport of mass, in particular metal-enriched gas, and energy out of galaxies and into the intergalactic medium. These outflows directly affect the chemical evolution of galaxies, and heat and enrich the intergalactic and intercluster medium. Currently, several basic problems preclude quantitative measurements of the impact of galactic winds: the unknown filling factors of, in particular, the soft X-ray-emitting gas prevent accurate measurements of densities, masses and energy content; multiphase temperature distributions of unknown complexity bias X-ray-determined abundances; unknown amounts of energy and mass may reside in hard to observe T~105K and T~107.5K phases; and the relative balance of thermal versus kinetic energy in galactic winds is not known. In an effort to address these problems, we perform an extensive hydrodynamical parameter study of starburst-driven galactic winds, motivated by the latest observation data on the best-studied starburst galaxy M82. We study how the wind dynamics, morphology and X-ray emission depend on the ISM distribution of the host galaxy, the starburst star formation history and strength, and the presence and distribution of mass-loading by dense clouds. We also investigate and discuss the influence of finite numerical resolution on the results of these simulations. We find that the soft X-ray emission from galactic winds comes from low filling factor (ηfactor that must be taken into account when attempting to constrain wind energetics observationally. We also find that galactic winds are efficient at transporting large amounts of energy out of the host galaxy, in contrast to their inefficiency at transporting mass out of star-forming galaxies.

  7. Characterization of the flowing afterglows of an N2 O2 reduced-pressure discharge: setting the operating conditions to achieve a dominant late afterglow and correlating the NOβ UV intensity variation with the N and O atom densities

    Science.gov (United States)

    Boudam, M. K.; Saoudi, B.; Moisan, M.; Ricard, A.

    2007-03-01

    The flowing afterglow of an N2-O2 discharge in the 0.6-10 Torr range is examined in the perspective of achieving sterilization of medical devices (MDs) under conditions ensuring maximum UV intensity with minimum damage to polymer-based MDs. The early afterglow is shown to be responsible for creating strong erosion damage, requiring that the sterilizer be operated in a dominant late-afterglow mode. These two types of afterglow can be characterized by optical emission spectroscopy: the early afterglow is distinguished by an intense emission from the N_{2}^{+} 1st negative system (band head at 391.4 nm) while the late afterglow yields an overpopulation of the v' = 11 ro-vibrational level of the N2(B) state, indicating a reduced contribution from the early afterglow N2 metastable species. We have studied the influence of operating conditions (pressure, O2 content in the N2-O2 mixture, distance of the discharge from the entrance to the afterglow (sterilizer) chamber) in order to achieve a dominant late afterglow that also ensures maximum and almost uniform UV intensity in the sterilization chamber. As far as operating conditions are concerned, moving the plasma source sufficiently far from the chamber entrance is shown to be a practical means for significantly reducing the density of the characteristic species of the early afterglow. Using the NO titration method, we obtain the (absolute) densities of N and O atoms in the afterglow at the NO injection inlet, a few cm before the chamber entrance: the N atom density goes through a maximum at approximately 0.3-0.5% O2 and then decreases, while the O atom density increases regularly with the O2 percentage. The spatial variation of the N atom (relative) density in the chamber is obtained by recording the emission intensity from the 1st positive system at 580 nm: in the 2-5 Torr range, this density is quite uniform everywhere in the chamber. The (relative) densities of N and O atoms in the discharge are determined by using

  8. Investigation on luminescence enhancement and decay characteristics of long afterglow nanophosphors for dark-vision display applications

    Energy Technology Data Exchange (ETDEWEB)

    Swati, G.; Chawla, S.; Mishra, S.; Rajesh, B.; Vijayan, N.; Sivaiah, B.; Dhar, A.; Haranath, D., E-mail: haranath@nplindia.org

    2015-04-01

    Graphical abstract: - Highlights: • Synthesis and structural characterization has been performed on long afterglow SrAl{sub 2}O{sub 4}:Eu{sup 2+}, Dy{sup 3+} nanophosphor having afterglow time of ∼12 h. • Studied the effect of various fuels used for synthesis of nanophosphors on the decay and luminescence characteristics. Interestingly, afterglow times varied significantly with different fuels used for the synthesis of the nanophosphor. • Excitation by different illuminants has profound influence on the luminescence intensity and afterglow times of the synthesized nanophosphor. • Such studies could be guidelines for appropriate usage of nanophosphor under different lighting environment. - Abstract: Long afterglow SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+} nanophosphors were synthesized via a facile but effectual auto-combustion technique followed by post-annealing treatment at elevated temperatures. The influence of various fuels during synthesis and thereafter improvement in the luminescence decay characteristics under various illuminant irradiations of long afterglow nanophosphors have been reported. Extensive studies on structural, morphological and luminescent properties of the as-synthesized afterglow nanophosphors have been presented. Powder X-ray diffraction studies confirm the presence of high-purity, single-phase monoclinic nanophosphors. HRTEM investigations confirm the formation of nanophosphors of particle size less than 50 nm. Photoluminescence emission is attributed to the characteristic d–f transition (4f{sup 6}5d{sup 1}→4f{sup 7}) of Eu{sup 2+} ions and was positioned at 512 nm. As-synthesized nanophosphors exhibit considerable confinement effects resulting into blue shift in emission maxima as compared to their bulk counterparts. The mechanism underlined for long afterglow has been discussed using trapping–detrapping model. The nanophosphor being multifunctional finds many interesting applications including dark-vision display

  9. In Vivo Targeting and Positron Emission Tomography Imaging of Tumor with Intrinsically Radioactive Metal-Organic Frameworks Nanomaterials.

    Science.gov (United States)

    Chen, Daiqin; Yang, Dongzhi; Dougherty, Casey A; Lu, Weifei; Wu, Hongwei; He, Xianran; Cai, Ting; Van Dort, Marcian E; Ross, Brian D; Hong, Hao

    2017-04-25

    Nanoscale metal-organic frameworks (nMOF) materials represent an attractive tool for various biomedical applications. Due to the chemical versatility, enormous porosity, and tunable degradability of nMOFs, they have been adopted as carriers for delivery of imaging and/or therapeutic cargos. However, the relatively low stability of most nMOFs has limited practical in vivo applications. Here we report the production and characterization of an intrinsically radioactive UiO-66 nMOF ((89)Zr-UiO-66) with incorporation of positron-emitting isotope zirconium-89 ((89)Zr). (89)Zr-UiO-66 was further functionalized with pyrene-derived polyethylene glycol (Py-PGA-PEG) and conjugated with a peptide ligand (F3) to nucleolin for targeting of triple-negative breast tumors. Doxorubicin (DOX) was loaded onto UiO-66 with a relatively high loading capacity (1 mg DOX/mg UiO-66) and served as both a therapeutic cargo and a fluorescence visualizer in this study. Functionalized (89)Zr-UiO-66 demonstrated strong radiochemical and material stability in different biological media. Based on the findings from cellular targeting and in vivo positron emission tomography (PET) imaging, we can conclude that (89)Zr-UiO-66/Py-PGA-PEG-F3 can serve as an image-guidable, tumor-selective cargo delivery nanoplatform. In addition, toxicity evaluation confirmed that properly PEGylated UiO-66 did not impose acute or chronic toxicity to the test subjects. With selective targeting of nucleolin on both tumor vasculature and tumor cells, this intrinsically radioactive nMOF can find broad application in cancer theranostics.

  10. Tuning THz emission properties of Bi2Sr2CaCu2O8+δ intrinsic Josephson junction stacks by charge carrier injection

    Science.gov (United States)

    Kizilaslan, O.; Rudau, F.; Wieland, R.; Hampp, J. S.; Zhou, X. J.; Ji, M.; Kiselev, O.; Kinev, N.; Huang, Y.; Hao, L. Y.; Ishii, A.; Aksan, M. A.; Hatano, T.; Koshelets, V. P.; Wu, P. H.; Wang, H. B.; Koelle, D.; Kleiner, R.

    2017-03-01

    We report on doping and undoping experiments of terahertz (THz) emitting intrinsic Josephson junction stacks, where the change in charge carrier concentration is achieved by heavy current injection. The experiments were performed on stand-alone structures fabricated from a Bi2Sr2CaCu2O{}8+δ single crystal near optimal doping. The stacks contained about 930 intrinsic Josephson junctions. On purpose, the doping and undoping experiments were performed over only a modest range of charge carrier concentrations, changing the critical temperature of the stack by less than 1 K. We show that both undoping and doping is feasible also for the large intrinsic Josephson junction stacks used for THz generation. Even moderate changes in doping introduce large changes in the THz emission properties of the stacks. The highest emission power was achieved after doping a pristine sample.

  11. A Leptonic-Hadronic Model for the Afterglow of Gamma-Ray Burst 090510

    Science.gov (United States)

    2010-11-20

    rights reserved. Printed in the U.S.A. A LEPTONIC– HADRONIC MODEL FOR THE AFTERGLOW OF GAMMA-RAY BURST 090510 Soebur Razzaque1 Space Science Division...combined leptonic– hadronic model of synchrotron radiation from an adiabatic blast wave. High-energy, !100 MeV, emission in our model is dominated by...escape the blast wave at early time, and their detection can provide evidence of a hadronic emission component dominating at high energies. Key words

  12. Weak Hard X-Ray Emission from Broad Absorption Line Quasars: Evidence for Intrinsic X-Ray Weakness

    DEFF Research Database (Denmark)

    Luo, B.; Brandt, W. N.; Alexander, D. M.

    2014-01-01

    We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z 330 times weaker than...... expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL...... quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three...

  13. The unexpected clustering of the optical afterglow luminosities

    CERN Document Server

    Nardini, M; Ghirlanda, G; Tavecchio, F; Firmani, C; Lazzati, D

    2006-01-01

    We studied the behaviour of the optical afterglow lightcurves of a sample of 24 Gamma--Ray Bursts (GRBs) with known redshift and published estimates of the optical extinction in the source frame, detected before the SWIFT satellite launch. We found an unexpected clustering of the optical luminosities at 12 hours in the source frame. The distribution of the optical luminosities is narrower than the distribution of X-ray luminosities at the same time. Few (3) bursts stand apart from the main optical distribution, being fainter by a factor of about 15. We also analysed the optical luminosities of the SWIFT burst with known redshift finding that the luminosity distribution is similar to the pre SWIFT GRBs one, even if they have a different mean redshift. These results can suggest the existence of a family of intrinsically optically under--luminous dark GRBs.

  14. Synthesis of ZnS:Ag,Co water-soluble blue afterglow nanoparticles and application in photodynamic activation

    Science.gov (United States)

    Ma, Lun; Zou, Xiaoju; Hossu, Marius; Chen, Wei

    2016-08-01

    Silver and cobalt co-doped ZnS (ZnS:Ag,Co) water-soluble afterglow nanoparticles were synthesized using a wet chemistry method followed by aging at room temperature. The nanoparticles had a cubic zinc blende structure with average sizes of approximately 4 nm and emitted a blue fluorescence emission centered at 441 nm due to radiative transitions from surface defects to Ag+ luminescent centers. Intense afterglow emission peaking at 475 nm from the obtained nanoparticles was observed and was red-shifted compared to the fluorescence emission peak. X-ray photoelectron spectroscopy revealed a large increase of O/S ratio, indicating a surface oxidation process during aging. The S vacancies produced accordingly may contribute to form more electron traps and enhance afterglow. The ZnS:Ag,Co afterglow nanoparticles have a very low dark-toxicity and are applied as a light source for photodynamic therapy activation by conjugating with protoporphyrin together. Our preliminary study has shown that the ZnS:Ag,Co afterglow nanoparticles can significantly reduce the x-ray dosage used in activation and thus may be a very promising candidate for future x-ray excited photodynamic therapy in deep cancer treatment.

  15. Gamma-ray burst afterglow theory

    CERN Document Server

    van Eerten, Hendrik

    2013-01-01

    It is by now fairly well established that gamma-ray burst afterglows result from initially relativistic outflows interacting with the medium surrounding the burster and emitting non-thermal radiation ranging from radio to X-rays. However, beyond that, many big and small questions remain about afterglows, with the accumulating amount of observational data at the various frequencies raising as many questions as they answer. In this review I highlight a number of current theoretical issues and how they fit or do not fit within our basic theoretical framework. In addition to theoretical progress I will also emphasize the increasing role and usefulness of numerical studies of afterglow blast waves and their radiation.

  16. Limits on the early afterglow phase of gamma-ray burst sources from TAROT-1

    CERN Document Server

    Boër, M; Bringer, M; Gendre, B; Klotz, A H; Malina, R; De Pacheco, J A F; Pedersen, H

    2001-01-01

    The T\\'elescope \\`a Action Rapide pour les Objets Transitoires (TAROT-1) has as prime objective the observation of the prompt and delayed emission of cosmic gamma-ray bursts (GRBs). We have performed a search for optical emission from 6 GRBs detected by BATSE. The positioning error circle was fully covered within typically thirty minutes after the trigger. No detection of the early afterglow phase was made, and magnitude limits in the range of $ \\mathrm{m}_{\\mathrm{R}} = 13-15 $ were estimated using 20s exposures. These limits are compared to optical afterglow data obtained in later phases and the results are interpreted in terms of source distances. They correspond to a median redshift of z = 0.5. With HETE-2 and the planned instrument upgrade, TAROT-1 will be able to detect the early optical emission of GRBs up to a redshift of the order of 5.

  17. Afterglows from Ring-Shaped Jet

    Science.gov (United States)

    Xu, M.; Huang, Y. F.; Kong, S. W.

    2008-10-01

    For gamma-ray bursts (GRBs), there may exist ring-shaped jet when the jet axis does not coincide with the spin axis of its source. Using some refined jet dynamics, we study multi-wavelength afterglow light curves for such ring-shaped jets. There is an obvious break in the afterglow light curve due to the beaming effect. We also investigate the effects of many key parameters on the light curves and then use our model to fit light curves of some GRBs.

  18. The afterglow of a relativistic shock breakout and low luminosity GRBs

    CERN Document Server

    Duran, Rodolfo Barniol; Piran, Tsvi; Sari, Re'em

    2014-01-01

    The prompt emission of low luminosity gamma-ray bursts ({\\it ll}GRBs) indicates that these events originate from a relativistic shock breakout. In this case we can estimate, based on the properties of the prompt emission, the energy distribution of the ejecta. We develop a general formalism to estimate the afterglow produced by synchrotron emission from the forward shock resulting from the interaction of this ejecta with the circum-burst matter. We assess whether this emission can produce the observed radio and X-ray afterglows of the available sample of 4 {\\it ll}GRBs. All 4 radio afterglows can be explained within this model, providing further support for shock breakouts being the origin of {\\it ll}GRBs. We find that in one of the {\\it ll}GRBs (GRB 031203) the predicted X-ray emission, using the same parameters that fit the radio, can explain the observed one. In another one (GRB 980425) the observed X-rays can be explained if we allow for a slight modification of the simplest model. For the last two cases ...

  19. Early afterglow detection in the Swift observations of GRB 050801

    CERN Document Server

    De Pasquale, M; Page, M J; Burrows, D N; Blustin, A J; Zane, S; Mason, K O; Roming, P W A; Palmer, D; Gehrels, N; Zhang, B; Pasquale, Massimiliano De

    2007-01-01

    We present results of Swift optical, UV and X-ray observations of the afterglow of GRB 050801. The source is visible over the full optical, UV and X-ray energy range of the Swift UVOT and XRT instruments.Both optical and X-ray lightcurves exhibit a broad plateau (\\Delta t/t ~ 1) during the first few hundred seconds after the gamma-ray event. We investigate the multiwavelength spectral and timing properties of the afterglow, and we suggest that the behaviour at early times is compatible with an energy injection by a newly born magnetar with a period of a few tenths of a millisecond, which keeps the forward shock refreshed over this short interval by irradiation. Reverse shock emission is not observed. Its suppression might be due to GRB ejecta being permeated by high magnetic fields, as expected for outflows powered by a magnetar.Finally, the multiwavelength study allows a determination of the burst redshift, z=1.56.

  20. Testing an unifying view of Gamma Ray Burst afterglows

    CERN Document Server

    Nardini, M; Ghirlanda, G; Celotti, A

    2009-01-01

    Four years after the launch the Swift satellite the nature of the Gamma Ray Bursts (GRBs) broadband afterglow behaviour is still an open issue ad the standard external shock fireball models cannot easily explain the puzzling combined temporal and spectral optical to X-ray behaviour of a large number of afterglows. We analysed the rest frame de-absorbed and K- corrected optical and X-ray multi-wavelength light-curves of a sample of 33 GRBs with known redshift and optical extinction at the host frame. We modelled their broadband behaviour as the sum of the standard forward shock emission due to the interaction of a fireball with the circum-burst medium and an additional component. We are able to obtain a good agreement with the observed light-curves despite their complexity and diversity and can also account for the lack of achromatic late times jet breaks in several GRBs and explain the presence of chromatic breaks. Even if the second component is treated in a phenomenological way, we can identify it as a "lat...

  1. The Interpretation and Implication of the Afterglow of GRB 060218

    CERN Document Server

    Fan, Y; Xu, D; Fan, Yizhong; Piran, Tsvi; Xu, Dong

    2006-01-01

    The nearby GRB 060216/SN 2006aj was an extremely long, weak and very soft GRB. While it was peculiar in many aspects its late ($>10^4$ sec) X-ray afterglow showed a canonical power law decay. Assuming that this component arises due to a relativistic blast wave decelerated by a circumburst matter we infer that the blast wave's kinetic energy was rather high, $5 \\times 10^{50}$ erg, close to what is seen in other GRBs. The lack of a "jet break" implies that the outflow was wide $\\theta_j \\sim 1$. The rather weak early optical emission rules out a dense circumburst wind profile. It also constrains the initial Lorentz factor to be significantly lower than usual, $\\Gamma_{\\rm ini}\\sim 15$. The observed afterglow suggests that the medium surrounding a massive star progenitor (up to distances of $\\sim 10^{17}-10^{18}$ cm) is not the expected dense stellar wind (a similar result was seen in many other bursts and in particular in GRB 030329). This implies that the progenitor's wind was weak during the last 100-1000 ye...

  2. An external-shock model for GRB afterglow 130427A

    CERN Document Server

    Panaitescu, A; Wozniak, P

    2013-01-01

    The complex multiwavelength emission of GRB afterglow 130427A (monitored in the radio up to 10 days, in the optical and X-ray until 50 days, and at GeV energies until 1 day) can be accounted for by a hybrid reverse-forward shock synchrotron model, with inverse-Compton emerging only above a few GeV. The high ratio of the early optical to late radio flux requires that the ambient medium is a wind and that the forward-shock synchrotron spectrum peaks in the optical at about 10 ks. The latter has two consequences: the wind must be very tenuous and the optical emission before 10 ks must arise from the reverse-shock, as suggested also by the bright optical flash that Raptor has monitored during the prompt emission phase (<100 s). The VLA radio emission is from the reverse-shock, the Swift X-ray emission is mostly from the forward-shock, but the both shocks give comparable contributions to the Fermi GeV emission. The weak wind implies a large blast-wave radius (8 t_{day}^{1/2} pc), which requires a very tenuous c...

  3. Afterglow of chlorophyll in vivo and photosynthesis

    NARCIS (Netherlands)

    Goedheer, J.C.

    1962-01-01

    Two pigment systems are involved in the afterglow of chlorophyll a-containing cells. Absorption in only one of these systems (promoting or “p” system) is effective in producing luminescence. If light is absorbed simultaneously by the other (quenching or “q” system), a decrease in luminescence result

  4. Gemini Spectroscopy of the Short GRB 130603B Afterglow and Host

    CERN Document Server

    Cucchiara, A; Perley, D A; Cenko, S B; Werk, J; Cao, Y; Bloom, J S; Cobb, B E

    2013-01-01

    We present early optical photometry and spectroscopy of the afterglow and host galaxy of the bright short-duration gamma-ray burst \\grb. Using our target-of-opportunity program on the Gemini South telescope, our prompt optical spectra reveal a strong trace from the afterglow superimposed on continuum and emission lines from the $z = 0.3568 \\pm 0.0005$ host galaxy. The combination of a relatively bright optical afterglow ($r^{\\prime} = 21.52$ at $\\Delta t = 8.4$\\,hr), together with an observed offset of 0\\farcs9 from the host nucleus (4.8 kpc projected distance at $z = 0.3568$), allow us to extract a relatively clean spectrum dominated by afterglow light -- the first \\textit{bona fide} short-duration GRB for which this has been possible. Furthermore, the spatially resolved spectrum allows us to constrain the properties of the explosion site directly, and compare these with the host galaxy nucleus, as well as other short-duration GRB host galaxies. We find that while the host is a relatively luminous ($L \\appro...

  5. Investigation on the effect of exposure time on scintillator afterglow for ultra-fast tomography acquisition

    Science.gov (United States)

    Zefreh, K. Z.; Welford, F. M.; Sijbers, Jan

    2016-12-01

    Thanks to the ultra-fast endstation of the TOMCAT beamline, it is possible to do a tomographic scan with a sub-second temporal resolution which allows following dynamic processes in 4D (3D space + time). This ultra- high-rate tomography acquisition, exploiting the distinctive peculiarities of synchrotron radiation, provides nondestructive investigation of many dynamic processes which were not possible in the past. For example a continuous tensile test has been conducted recently in-situ for the first time with a frequency of 20 tomograms per second (20 Hz acquisition frequency). In the ultra-fast endstation a scintillator is used to convert X-ray to visible photons that can be detected by the camera. However, this conversion is not ideal and the scintillator response decays exponentially with afterglow. Afterglow can cause resolution degradation and artifacts (such as ring and band) especially with high rotation speed. On the other hand, to achieve a higher scan speed, thicker scintillators are more common because they result in higher emission intensities that can compensate the short exposure time in fast scans. However, the resolution deteriorates as the scintillator's thickness increases and thicker scintillators show higher afterglow. Performing many ultra-fast scans at the TOMCAT beamline with different acquisition rate, we demonstrate how the exposure time effects on the projection data and reconstructed images. Using two different thicknesses of LAG scintillator we also investigate the afterglow artifacts for different acquisition rate and exposure time.

  6. GRB 110715A: The peculiar multiwavelength evolution of the first afterglow detected by ALMA

    CERN Document Server

    Sánchez-Ramírez, R; Jóhannesson, G; Murphy, Tara; Postigo, A de Ugarte; Gorosabel, J; Kann, D A; Krühler, T; Oates, S R; Japelj, J; Thöne, C C; Lundgren, A; Perley, D A; Malesani, D; Monsalvo, I de Gregorio; Castro-Tirado, A J; D'Elia, V; Fynbo, J P U; Garcia-Appadoo, D; Goldoni, P; Greiner, J; Hu, Y -D; Jelínek, M; Jeong, S; Kamble, A; Klose, S; Kuin, N P M; Llorente, A; Martín, S; Guelbenzu, A Nicuesa; Rossi, A; Schady, P; Sparre, M; Sudilovsky, V; Tello, J C; Updike, A; Wiersema, K; Zhang, B -B

    2016-01-01

    We present the extensive follow-up campaign on the afterglow of GRB 110715A at 17 different wavelengths, from X-ray to radio bands, starting 81 seconds after the burst and extending up to 74 days later. We performed for the first time a GRB afterglow observation with the ALMA observatory. We find that the afterglow of GRB 110715A is very bright at optical and radio wavelengths. We use optical and near infrared spectroscopy to provide further information about the progenitor's environment and its host galaxy. The spectrum shows weak absorption features at a redshift $z$ = 0.8225, which reveal a host galaxy environment with low ionization, column density and dynamical activity. Late deep imaging shows a very faint galaxy, consistent with the spectroscopic results. The broadband afterglow emission is modelled with synchrotron radiation using a numerical algorithm and we determine the best fit parameters using Bayesian inference in order to constrain the physical parameters of the jet and the medium in which the ...

  7. Optical-infrared flares and radio afterglows by Jovian planets inspiraling into their host stars

    Science.gov (United States)

    Yamazaki, Ryo; Hayasaki, Kimitake; Loeb, Abraham

    2017-04-01

    When a planet inspirals into its host star, it releases gravitational energy, which is converted into an expanding bubble of hot plasma. We study the radiation from the bubble and show that it includes prompt optical-infrared emission and a subsequent radio afterglow. The prompt emission from M31 and the Large Magellanic Cloud is detectable by optical-near-infrared transient surveys with a large field of view. The subsequent radio afterglows are detectable for 103-104 yr. The event rate depends on uncertain parameters in the formation and dynamics of giant planets. Future observations of the rate will constrain related theoretical models. If the event rate is high ( ≳ a few events per year), the circumstellar disc must typically be massive, as suggested by recent numerical simulations.

  8. Early Optical Polarization of Forward Shock Afterglow of GRB 091208B

    CERN Document Server

    Uehara, T; Kawabata, K S; Chiyonobu, S; Fukazawa, Y; Ikejiri, Y; Inoue, T; Itoh, R; Komatsu, T; Miyamoto, H; Mizuno, T; Nagae, O; Nakaya, H; Ohsugi, T; Sakimoto, K; Sasada, M; Tanaka, H; Uemura, M; Yamanaka, M; Yamashita, T; Yamazaki, R; Yoshida, M

    2012-01-01

    We report that the optical polarization in the afterglow of GRB 091208B is measured at t = 149 - 706 s after the burst trigger, and the polarization degree is P = 10.4% +/- 2.5%. The optical light curve at this time shows a power-law decay with index -0.75 +/- 0.02, which is interpreted as the forward shock synchrotron emission, and thus this is the first detection of the early-time optical polarization in the forward shock (rather than that in the reverse shock reported by Steele et al. (2009). This detection disfavors the afterglow model in which the magnetic fields in the emission region are random on the plasma skin depth scales, such as amplified by the plasma instabilities, e.g., Weibel instability. We suggest that the fields are amplified by the magnetohydrodynamic instabilities, which would be tested by future observations of the temporal changes of the polarization degrees and angles for other bursts.

  9. Long afterglow property of Er{sup 3+} doped Ca{sub 2}SnO{sub 4} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dongyun, E-mail: dyz@sit.edu.cn; Shi, Mingming; Sun, Yiwen; Guo, Yunyun; Chang, Chengkang

    2016-05-15

    A novel green emitting long afterglow phosphor, Er{sup 3+} -doped Ca{sub 2}SnO{sub 4} (Ca{sub 2}SnO{sub 4}:Er{sup 3+}), was prepared successfully via a traditional high temperature solid–state reaction method. Its properties have been characterized and analyzed by utilizing x-ray diffraction (XRD), photoluminescence spectroscope (PLS), afterglow decay curve (ADC) and thermal luminescence spectroscope (TLS). Three main emission peaks of PLS locate at 524, 550 and 668 nm, corresponding to CIE chromaticity coordinates of x = 0.326, y = 0.6592. An optimal doping concentration of Er{sup 3+} of 2% was determined. The Ca{sub 2}SnO{sub 4}:Er{sup 3+} phosphors showed a typical triple-exponential afterglow decay behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of Ca{sub 2}SnO{sub 4}:2 mol% Er{sup 3+} phosphors was generated by the suitable electron or hole traps which were resulted from the doping the Ca{sub 2}SnO{sub 4} host with rare-earth ions (Er{sup 3+}). - Highlights: • A novel green emitting long afterglow phosphor, Ca{sub 2}SnO{sub 4}:Er{sup 3+}, was prepared. • An optimal doping concentration of Er{sup 3+} of 2% was determined. • After the UV source was turned off, the Ca{sub 2}SnO{sub 4}:Er{sup 3+} showed a typical triple-exponential afterglow decay behavior. • CIE chromaticity coordinates results confirmed a green light emitting of the Ca{sub 2}SnO{sub 4}:Er{sup 3+}. • The persistent afterglow of the Ca{sub 2}SnO{sub 4}:Er{sup 3+} was attributed to suitable electron or hole traps.

  10. The optical afterglow and host galaxy of GRB 000926

    DEFF Research Database (Denmark)

    Fynbo, J.U.; Gorosabel, J.; Dall, T.H.;

    2002-01-01

    In this paper we illustrate with the case of GRB 000926 how Gamma Ray Bursts (GRBs) can be used as cosmological lighthouses to identify and study star forming galaxies at high redshifts. The optical afterglow of the burst was located with optical imaging at the Nordic Optical Telescope 20.7 hours...... after the burst. Rapid follow-up spectroscopy allowed the determination of the redshift of the burst and a measurement of the host galaxy HI-column density in front of the burst. With late-time narrow band Lyalpha as well as broad band imaging, we have studied the emission from the host galaxy and found...... that it is a strong Lyalpha emitter in a state of active star formation....

  11. Afterglow-reabsorbed H/sub alpha/ line delay effect in an expanding laser plasma

    Energy Technology Data Exchange (ETDEWEB)

    Derzhiev, V.I.; Zhidkov, A.G.; Maiorov, S.A.; Yakovlenko, S.I.

    1987-11-28

    The absorption of H/sub ..cap alpha../ line radiation is shown to lead to delay and even to non-monotonic afterglowing if observed along the 'line' of the expanding laser plasma. This makes it possible to explain the emission character of the H/sub ..cap alpha../ line of the O VIII ion (lambda = 10.2 nm) in experiments with 'Novette' set-ups.

  12. Modelling the Multi-band Afterglow of GRB 091127: Evidence of a Hard Electron Energy Spectrum with an Injection Break

    CERN Document Server

    Zhang, Qiang; Zong, Hong-Shi

    2016-01-01

    The afterglow of GRBs is believed to originate from the synchrotron emission of shock-accelerated electrons produced by the interaction between the outflow and the external medium. The accelerated electrons are usually assumed to follow a power law energy distribution with an index of $p$. Observationally, although most GRB afterglows have a $p$ larger than 2, there are still a few GRBs suggestive of a hard ($p<2$) electron spectrum. GRB 091127, with well-sampled broad-band afterglow data, shows evidence of a hard electron spectrum and strong spectral evolution, with a spectral break moving from high to lower energies. The spectral break evolves very fast and cannot be explained by the cooling break in the standard afterglow model, unless evolving microphysical parameters are assumed. Besides, the multi-band afterglow light curves show an achromatic break at around 33 ks. Based on the model of a hard electron spectrum with an injection break, we interpret the observed spectral break as the synchrotron freq...

  13. Gamma-Ray Burst Afterglows from Realistic Fireballs

    OpenAIRE

    Dai, Z. G.; Huang, Y. F.; Lu, T

    1998-01-01

    A GRB afterglow has been commonly thought to be due to continuous deceleration of a postburst fireball. Many analytical models have made simplifications for deceleration dynamics of the fireball and its radiation property, although they are successful at explaining the overall features of the observed afterglows. We here propose a model for a GRB afterglow in which the evolution of a postburst fireball is in an intermediate case between the adiabatic and highly radiative expansion. In our mod...

  14. From Engine to Afterglow: Collapsars Naturally Produce Top-Heavy Jets and Early-Time Plateaus in Gamma Ray Burst Afterglows

    CERN Document Server

    Duffell, Paul C

    2014-01-01

    We demonstrate that the steep decay and long plateau in the early phases of gamma ray burst (GRB) afterglows are naturally produced in the collapsar model, by a means ultimately related to the dynamics of relativistic jet propagation through a massive star. We present hydrodynamical simulations which start from a collapsar engine and evolve all the way through the late afterglow phase. The resultant outflow includes a jet core which is highly relativistic after breaking out of the star, but becomes baryon-loaded and less relativistic after colliding with a massive outer shell, corresponding to mass from the stellar atmosphere of the progenitor star which became trapped in front of the jet core at breakout. The prompt emission produced before or during this collision would then have the signature of a high Lorentz factor jet, but the afterglow is produced by the amalgamated post-collision ejecta which has more inertia than the original highly relativistic jet core and thus has a delayed deceleration. This natu...

  15. The Rapidly Flaring Afterglow of the Very Bright and Energetic GRB 070125

    CERN Document Server

    Updike, Adria C; Nysewander, Melissa C; Fruchter, Andrew S; Kann, D Alexander; Klose, Sylvio; Milne, Peter A; Williams, G Grant; Zheng, Weikang; Hergenrother, Carl W; Prochaska, Jason X; Halpern, Jules P; Mirabal, Nestor; Thorstensen, John R; van der Horst, Alexander J; Starling, Rhaana L C; Racusin, Judith L; Burrows, David N; Kuin, N P M; Roming, Peter W A; Bellm, Eric; Hurley, Kevin; Li, Weidong; Filippenko, Alexei V; Blake, Cullen; Starr, Dan; Falco, Emilio E; Brown, Warren R; Dai, Xinyu; Deng, Jinsong; Xin, Liping; Qiu, Yulei; Wei, Jianyan; Urata, Yuji; Nanni, Domenico; Maiorano, Elisabetta; Palazzi, Eliana; Greco, Giuseppe; Bartolini, Corrado; Guarnieri, Adriano; Piccioni, Adalberto; Pizzichini, Graziella; Terra, Federica; Misra, Kuntal; Bhatt, B C; Anupama, G C; Fan, X; Jiang, L; Wijers, Ralph A M J; Reichart, Dan E; Eid, Hala A; Bryngelson, Ginger; Puls, Jason; Goldthwaite, R C; Hartmann, Dieter H

    2008-01-01

    We report on multi-wavelength observations, ranging from the X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O I, Si II, and C IV, implying a likely redshift of z = 1.547. The well-sampled light curves, in particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days, corresponding to a jet opening angle of ~7.0 degrees, and implying an intrinsic GRB energy in the 1 - 10,000 keV band of around E = (6.3 - 6.9)x 10^(51) erg (based on the fluences measured by the gamma-ray detectors of the IPN network). GRB 070125 is among the brightest afterglows observed to date. The spectral energy distribution implies a host extinction of Av < 0.9 mag. Two rebrightening episodes are observed, one with excellent time coverage, showing an increase in flux of 56% in ~8000 seconds. The evolution of the afterglow light curve is achromatic at all times. Late-time observations of the afterglow do not show eviden...

  16. The GRB afterglow onset observed by REM: fireball Lorentz factor and afterglow fluence

    CERN Document Server

    Malesani, Daniele; Vergani, Susanna; Covino, Stefano

    2007-01-01

    We report observations of the early light curves of GRB 060418 and GRB 060607A, carried out with the pink robotic telescope REM. A clear peak is detected for both events, which is interpreted as the onset of the afterglow, that is the time at which the fireball starts decelerating. This detection allows to directly measure the initial fireball Lorentz factor, which was found to be Gamma_0 ~ 400 for both events, fully confirming the ultrarelativistic nature of gamma-ray burst fireballs. Sampling the light curve before the peak also allows to compute the bolometric fluence of the afterglow, which is 16% of the prompt one in the case of GRB 060418.

  17. Luminescence of divalent europium activated spinels synthesized by combustion and the enhanced afterglow by dysprosium incorporation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Haoyi, E-mail: manofchina@gmail.com; Jin, Yahong

    2016-05-01

    Herein we report a luminescent phenomenon of Eu{sup 2+} in the spinel MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} samples which are successfully synthesized via a combustion method. The XRD shows cubic spinel structure is obtained from the prepared samples. The mean crystal sizes estimated from XRD data are 30 and 10 nm for MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} respectively, and the large grain particles are the agglomeration of crystallites. The Eu{sup 2+} ions show a blue emission at around 480 nm and an afterglow phenomenon is observed after the removal of excitation. The afterglow spectrum of MgAl{sub 2}O{sub 4}: Eu{sup 2+}, Dy{sup 3+} shows two emissions at 480 and 520 nm while only one at 480 nm is observed in ZnAl{sub 2}O{sub 4}: Eu{sup 2+}, Dy{sup 3+}. The afterglow intensity and the persisting duration can be substantially enhanced by the Dy{sup 3+} incorporation because the trapping ability of the electron traps is reinforced. This is confirmed by the TL curves of the samples.

  18. Dark Bursts in the Swift Era: The Palomar 60 inch-Swift Early Optical Afterglow Catalog

    CERN Document Server

    Cenko, S B; Harrison, F A; Fox, D B; Kulkarni, S R; Kasliwal, M M; Ofek, E O; Rau, A; Gal-Yam, A; Frail, D A; Moon, D -S

    2008-01-01

    We present multi-color optical observations of long-duration gamma-ray bursts (GRBs) made over a three year period with the robotic Palomar 60 inch telescope (P60). Our sample consists of all 29 events discovered by Swift for which P60 began observations less than one hour after the burst trigger. We were able to recover 80% of the optical afterglows from this prompt sample, and we attribute this high efficiency to our red coverage. Like Melandri et al. (2008), we find that a significant fraction (~ 50%) of Swift events show a suppression of the optical flux with regards to the X-ray emission (so-called "dark" bursts). Our multi-color photometry demonstrates this is likely due in large part to extinction in the host galaxy. We argue that previous studies, by selecting only the brightest and best-sampled optical afterglows, have significantly underestimated the amount of dust present in typical GRB environments.

  19. Afterglow characteristics of CaTiO3: Pr3+ prepared by solar furnace

    Science.gov (United States)

    Katayama, Yumiko; Tanabe, Setsuhisa

    2011-05-01

    We have prepared polycrystalline CaTiO3: Pr3+ showing long-lasting phosphorescence by melting method using a solar furnace. Emission, excitation spectra, phosphorescence decay and thermoluminescence were compared with samples prepared by conventional solid-state reaction in conventional electric furnace (EF) at 1200 °C, 5 h in air. The color of the sample prepared by solar furnace (SF-AM) was dark brownish. After heat treatment at 800°C, 5h in air atmosphere, a decolorized sample (SF-HT) was obtained. All samples showed Pr3+:1D2 → 3H4 fluorescence at 613 nm and corresponding afterglow phosphorescence. The SF-AM and SF-HT showed much higher PLE intensity of Pr3+:3PJ bands in blue region than EF. CaTiO3:Pr3+ made by a solar furnace has a potential to be a red afterglow phosphor even under visible excitation.

  20. The Early X-ray Afterglows of Optically Bright and Dark Gamma-Ray Bursts

    Institute of Scientific and Technical Information of China (English)

    Yi-Qing Lin

    2006-01-01

    A systematic study on the early X-ray afterglows of both optically bright and dark gamma-ray bursts (B-GRBs and D-GRBs) observed by Swift is presented. Our sample includes 25 GRBs of which 13 are B-GRBs and 12 are D-GRBs. Our results show that the distributions of the X-ray afterglow fluxes (Fx), the gamma-ray fluxes (Sγ), and the ratio (Rγ,X) are similar for the two kinds of GRBs, that any observed differences should be simply statistical fluctuation. These results indicate that the progenitors of the two kinds of GRBs are of the same population with comparable total energies of explosion. The suppression of optical emission in the D-GRBs should result from circumburst but not from their central engine.

  1. The Growth, Polarization, and Motion of the Radio Afterglow from the Giant Flare from SGR 1806-20

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, G

    2005-04-20

    The extraordinary giant flare (GF) of 2004 December 27 from the soft gamma repeater (SGR) 1806-20 was followed by a bright radio afterglow. We present an analysis of VLA observations of this radio afterglow from SGR1806-20, consisting of previously reported 8.5 GHz data covering days 7 to 20 after the GF, plus new observations at 8.5 and 22 GHz from day 24 to 81. For a symmetric outflow, we find a deceleration in the expansion, from {approx}4.5 mas/day to <2.5 mas/day. The time of deceleration is roughly coincident with the rebrightening in the radio light curve, as expected to result when the ejecta from the GF sweeps up enough of the external medium, and transitions from a coasting phase to the Sedov-Taylor regime. The radio afterglow is elongated and maintains a 2:1 axis ratio with an average position angle of -40{sup o} (north through east), oriented perpendicular to the average intrinsic linear polarization angle. We also report on the discovery of motion in the flux centroid of the afterglow, at an average velocity of 0.26 {+-} 0.03 c (assuming a distance of 15 kpc) at a position angle of -45{sup o}. This motion, in combination with the growth and polarization measurements, suggests an initially asymmetric outflow, mainly from one side of the magnetar.

  2. Thermal Electrons in Gamma-Ray Burst Afterglows

    Science.gov (United States)

    Ressler, Sean M.; Laskar, Tanmoy

    2017-08-01

    To date, nearly all multi-wavelength modeling of long-duration γ-ray bursts has ignored synchrotron radiation from the significant population of electrons expected to pass the shock without acceleration into a power-law distribution. We investigate the effect of including the contribution of thermal, non-accelerated electrons to synchrotron absorption and emission in the standard afterglow model, and show that these thermal electrons provide an additional source of opacity to synchrotron self-absorption, and yield an additional emission component at higher energies. The extra opacity results in an increase in the synchrotron self-absorption frequency by factors of 10-100 for fiducial parameters. The nature of the additional emission depends on the details of the thermal population, but is generally observed to yield a spectral peak in the optical brighter than radiation from the nonthermal population by similar factors a few seconds after the burst, remaining detectable at millimeter and radio frequencies several days later.

  3. Investigation on luminescence enhancement and decay characteristics of long afterglow nanophosphors for dark-vision display applications

    Science.gov (United States)

    Swati, G.; Chawla, S.; Mishra, S.; Rajesh, B.; Vijayan, N.; Sivaiah, B.; Dhar, A.; Haranath, D.

    2015-04-01

    Long afterglow SrAl2O4:Eu2+,Dy3+ nanophosphors were synthesized via a facile but effectual auto-combustion technique followed by post-annealing treatment at elevated temperatures. The influence of various fuels during synthesis and thereafter improvement in the luminescence decay characteristics under various illuminant irradiations of long afterglow nanophosphors have been reported. Extensive studies on structural, morphological and luminescent properties of the as-synthesized afterglow nanophosphors have been presented. Powder X-ray diffraction studies confirm the presence of high-purity, single-phase monoclinic nanophosphors. HRTEM investigations confirm the formation of nanophosphors of particle size less than 50 nm. Photoluminescence emission is attributed to the characteristic d-f transition (4f65d1→4f7) of Eu2+ ions and was positioned at 512 nm. As-synthesized nanophosphors exhibit considerable confinement effects resulting into blue shift in emission maxima as compared to their bulk counterparts. The mechanism underlined for long afterglow has been discussed using trapping-detrapping model. The nanophosphor being multifunctional finds many interesting applications including dark-vision display, energy storage, fingerprint detection, in vivo and in vitro biological staining, etc.

  4. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H. J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

    2010-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on circumstance

  5. Shocked by GRB 970228: the afterglow of a cosmological fireball

    NARCIS (Netherlands)

    Wijers, R.A.M.J.; Rees, M.J.; Meszaros, P.

    1997-01-01

    The location accuracy of the BeppoSAX Wide Field Cameras and acute ground-based follow-up have led to the detection of a decaying afterglow in X-rays and optical light following the classical gamma-ray burst GRB 970228. The afterglow in X-rays and optical light fades as a power law at all wavelength

  6. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H. J.; Meliani, Z.; Wijers, Ramj; Keppens, R.

    2011-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on circumstance

  7. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H.J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

    2012-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on circumstance

  8. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H. J.; Meliani, Z.; Wijers, Ramj; Keppens, R.

    2011-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

  9. Jet simulations and gamma-ray burst afterglow jet breaks

    NARCIS (Netherlands)

    van Eerten, H. J.; Meliani, Z.; Wijers, R.A.M.J.; Keppens, R.

    2010-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on

  10. Characterization of the flowing afterglows of an N{sub 2}-O{sub 2} reduced-pressure discharge: setting the operating conditions to achieve a dominant late afterglow and correlating the NO{sub {beta}} UV intensity variation with the N and O atom densities

    Energy Technology Data Exchange (ETDEWEB)

    Boudam, M K [Groupe de Physique des Plasmas, Universite de Montreal, CP 6128, Succursale Centre-Ville, Montreal H3C 3J7, Quebec (Canada); Saoudi, B [Groupe de Physique des Plasmas, Universite de Montreal, CP 6128, Succursale Centre-Ville, Montreal H3C 3J7, Quebec (Canada); Moisan, M [Groupe de Physique des Plasmas, Universite de Montreal, CP 6128, Succursale Centre-Ville, Montreal H3C 3J7, Quebec (Canada); Ricard, A [Centre de Physique Atomique de Toulouse (CPAT), 118, route de Narbonne, Universite Paul Sabatier, 31062-Toulouse (France)

    2007-03-21

    The flowing afterglow of an N{sub 2}-O{sub 2} discharge in the 0.6-10 Torr range is examined in the perspective of achieving sterilization of medical devices (MDs) under conditions ensuring maximum UV intensity with minimum damage to polymer-based MDs. The early afterglow is shown to be responsible for creating strong erosion damage, requiring that the sterilizer be operated in a dominant late-afterglow mode. These two types of afterglow can be characterized by optical emission spectroscopy: the early afterglow is distinguished by an intense emission from the N{sub 2}{sup +} 1st negative system (band head at 391.4 nm) while the late afterglow yields an overpopulation of the v' = 11 ro-vibrational level of the N{sub 2}(B) state, indicating a reduced contribution from the early afterglow N{sub 2} metastable species. We have studied the influence of operating conditions (pressure, O{sub 2} content in the N{sub 2}-O{sub 2} mixture, distance of the discharge from the entrance to the afterglow (sterilizer) chamber) in order to achieve a dominant late afterglow that also ensures maximum and almost uniform UV intensity in the sterilization chamber. As far as operating conditions are concerned, moving the plasma source sufficiently far from the chamber entrance is shown to be a practical means for significantly reducing the density of the characteristic species of the early afterglow. Using the NO titration method, we obtain the (absolute) densities of N and O atoms in the afterglow at the NO injection inlet, a few cm before the chamber entrance: the N atom density goes through a maximum at approximately 0.3-0.5% O{sub 2} and then decreases, while the O atom density increases regularly with the O{sub 2} percentage. The spatial variation of the N atom (relative) density in the chamber is obtained by recording the emission intensity from the 1st positive system at 580 nm: in the 2-5 Torr range, this density is quite uniform everywhere in the chamber. The (relative

  11. Effect of mixing process on the luminescent properties of SrAl_2O_4:Eu~(2+),Dy~(3+) long afterglow phosphors

    Institute of Scientific and Technical Information of China (English)

    吕霄; 孙猛; 张俊英; 王天民

    2010-01-01

    A new mixing method was developed for solid-state reaction synthesis of SrAl2O4:Eu2+,Dy3+ long afterglow phosphors.The morphology and crystal structure of the phosphors were analyzed with scanning electron microscope(SEM) and X-ray diffractometer(XRD).The excitation and emission spectra of the long afterglow phosphors were measured,and the main emission band was around 514 nm.The decay time of the product was measured and compared with the phosphors prepared using dry-mixing method and wet-mixing method.It ...

  12. On the afterglow from the receding jet of γ-ray bursts

    Science.gov (United States)

    Wang, X.; Huang, Y. F.; Kong, S. W.

    2009-10-01

    According to popular progenitor models of gamma-ray bursts, twin jets should be launched by the central engine, with a forward jet moving toward the observer and a receding jet (or the counter jet) moving backwardly. However, in calculating the afterglows, usually only the emission from the forward jet is considered. Here we present a detailed numerical study on the afterglow from the receding jet. Our calculation is based on a generic dynamical description, and includes some delicate ingredients such as the effect of the equal arrival time surface. It is found that the emission from the receding jet is generally rather weak. In radio bands, it usually peaks at a time t ≥ 1000 d, with the peak flux nearly 4 orders of magnitude lower than the peak flux of the forward jet. Also, it usually manifests as a short plateau in the total afterglow light curve, but not as an obvious rebrightening as once expected. In optical bands, the contribution from the receding jet is even weaker, with the peak flux being ~23 mag lower than the peak flux of the forward jet. We thus argue that the emission from the receding jet is very difficult to detect. However, in some special cases, i.e., when the circum-burst medium density is very high, or if the parameters of the receding jet are quite different from those of the forward jet, the emission from the receding jet can be significantly enhanced and may still emerge as a marked rebrightening. We suggest that the search for receding jet emission should mostly concentrate on nearby gamma-ray bursts, and the observation campaign should last for at least several hundred days for each event.

  13. Dust Extinction Curves and Ly-$\\alpha$ Forest Flux Deficits for Use in Modeling GRB Afterglows and All Other Extragalactic Point Sources

    CERN Document Server

    Reichart, D E

    1999-01-01

    Since gamma-ray burst afterglows were first detected in 1997, the relativistic fireball model has emerged as the leading theoretical explanation of the afterglows. In this paper, we present a very general, Bayesian inference formalism with which this, or any other, afterglow model can be tested, and with which the parameter values of acceptable models can be constrained, given the available photometry. However, before model comparison or parameter estimation can be attempted, one must also consider the physical processes that affect the afterglow as it propagates along the line of sight from the burst source to the observer. Namely, how does extinction by dust, both in the host galaxy and in our galaxy, and absorption by the Ly-alpha forest and by H I in the host galaxy, change the intrinsic spectrum of the afterglow? Consequently, we also present in this paper a very general, eight-parameter dust extinction curve model, and a two-parameter model of the Ly-alpha forest flux deficit versus redshift distributio...

  14. "Anomalous" Optical GRB Afterglows are Common: Two z~4 Bursts, GRB 060206 and 060210

    CERN Document Server

    Stanek, K Z; Calkins, M L; Dai, X; Dobrzycki, A; Garnavich, P M; Hao, H; Howk, C; Matheson, T; Prieto, J L; Serven, J; Worthey, G

    2006-01-01

    We report on two recent z~4 gamma-ray bursts (GRBs), GRB 060206 and GRB 060210, for which we have obtained well-sampled optical light curves. Our data, combined with early optical data reported in the literature, shows unusual behavior for both afterglows. In R-band GRB 060206 (z=4.045) experienced a slow early decay, followed by a rapid increase in brightness by factor ~2.5 about 1 hour after the burst. Its afterglow then faded in a broken power-law fashion, with a smooth break at t_b=0.6 days, but with additional, less dramatic (~10%) ``bumps and wiggles'', well detected in the densely sampled light curve. The R-band afterglow of GRB 060210 (z=3.91) is also unusual: the light curves was more or less flat between 60 and 300 sec after the burst, followed by ~70% increase at ~600 sec after the burst, after which the light curve declined as a \\~t^{-1.3} power-law. The early X-ray light curve of GRB 060210 exhibited two sharp flares, but later X-ray emission fades in the same fashion as the optical light curve. ...

  15. Discovery of the Low-Redshift Afterglow of GRB 011121 and Its Progenitor Supernova 2001ke

    Science.gov (United States)

    Garnavich, P. M.; Stanek, K. Z.; Wyrzykowski, L.; Infante, L.; Bendek, E.; Holland, S. T.; Bersier, D.; Jha, S.; Matheson, T.; Kirshner, R. P.; Phillips, M. M.; Krisciunas, K.; Carlberg, R.

    2002-05-01

    We identify and present the first optical observations of the afterglow of the Gamma-Ray Burst (GRB) 011121. Images were obtained with the OGLE 1.3m telescope in BVRI passbands, starting 10.3;hours after the burst. The temporal analysis of our data indicates a steep decay, independent of wavelength with Fν t{-1.72+/- 0.05}. There is no evidence for a break in the light curve earlier than 2.5 days after the burst. The spectral energy distribution determined from the early broad-band photometry is a power-law with Fν ν {-0.46+/- 0.10} after correcting for a large Galactic extinction. Spectra, obtained with the Magellan 6.5m Baade telescope, reveal narrow emission lines from the host galaxy and these provide a redshift of z=0.36, which is the lowest measured redshift for an optical afterglow. We also present late R and J-band observations of the afterglow ~ 14;days after the burst. The late-time photometry shows a large deviation from the initial decline and our data combined with Hubble Space Telescope photometry provide strong evidence for a supernova peaking less than 10 rest-frame days after the GRB. This is the best evidence to date that classical, long gamma-ray bursts are generated by core-collapse supernovae. This work is partially supported by NASA LTSA grant NAG5-9364.

  16. GRB afterglows: Dust extinction properties from the low to high redshift universe

    Science.gov (United States)

    Zafar, Tayyaba

    2016-11-01

    Long-duration Gamma-ray bursts (GRBs) are excellent probes to study dust extinction due to their occurrence in star-forming regions and having simple synchrotron emission spectra. Inclusion of spectroscopic data to the GRB X-ray to the infrared spectral energy distribution (SED) could better define the continuum and confirm extinction feature. A preliminary SED analysis of GRB afterglows targeted with the VLT/X-Shooter spectrograph finds that all the 60% of extinguished bursts fit-well with featureless extinction curves. The longer wavelength coverage from ultraviolet to the near-infrared of X-Shooter helps to derive individual extinction curves and determine the total-to-selective extinction, RV precisely, suggesting extinction curves steeper (with a mean of RV = 2.66 ± 0.10) than the Small Magellanic Cloud. Moreover, addition of more data to the study of dust-to-metals ratios in GRB afterglows, quasar absorbers, and multiply lensed galaxies still shows the dust-to-metals ratios close to the Galactic value (with a mean value of log - 21.2cm-2mag-1), hinting short time delay between metals and dust formation. Such studies demonstrate the strength of using GRB afterglows to study dust origin and its properties the from low to high redshift Universe.

  17. Multicolor observations of the afterglow of the short/hard GRB 050724

    CERN Document Server

    Malesani, D; D'Avanzo, P; D'Elia, V; Fugazza, D; Piranomonte, S; Ballo, L; Campana, S; Stella, L; Tagliaferri, G; Antonelli, L A; Chincarini, G; Della Valle, M; Goldoni, P; Guidorzi, C; Israel, G L; Lazzati, D; Melandri, A; Romano, P; Stratta, G; Vergani, S D

    2007-01-01

    New information on short/hard gamma-ray bursts (GRBs) is being gathered thanks to the discovery of their optical and X-ray afterglows. However, some key aspects are still poorly understood, including the collimation level of the outflow, the duration of the central engine activity, and the properties of the progenitor systems. We want to constrain the physical properties of the short GRB 050724 and of its host galaxy, in turn drawing some inferences on the global short GRB population. We present optical observations of the afterglow of GRB 050724 and of its host galaxy, significantly expanding the existing dataset for this event. We compare our results with models, complementing them with available measurements in the literature. Including X-ray data, we study the afterglow light curve and spectrum. We also present observations of the host galaxy. The observed optical emission was likely related to the large flare observed in the X-ray light curve. The apparent steep decay was therefore not due to the jet eff...

  18. Intrinsic spontaneous emission-induced fluctuations of the output optical beam power and phase in a diode amplifier

    Science.gov (United States)

    Bogatov, A. P.; Drakin, A. E.; D'yachkov, N. V.; Gushchik, T. I.

    2016-08-01

    Output optical beam intensity and phase fluctuations are analysed in a classical approach to describing the propagation and amplification of spontaneous emission in the active region of a laser diode with a gain saturated by input monochromatic light. We find their spectral densities and dispersion and the correlation coefficient of the two-dimensional probability distribution function of the fluctuations.

  19. Weak Hard X-Ray Emission from Two Broad Absorption Line Quasars Observed with NuStar: Compton-Thick Absorption or Intrinsic X-Ray Weakness?

    Science.gov (United States)

    Luo, B.; Brandt, W. N.; Alexander, D. M.; Harrison, F. A.; Stern, D.; Bauer, F. E.; Boggs, S. E.; Christensen, F. E.; Comastri, A.; Craig, W. W..; Fabian, A. C.; Farrah, D.; Fiore, F.; Fuerst, F.; Grefenstette, B. W.; Hailey, C. J.; Hickox, R.; Madsen, K. K.; Matt, G.; Ogle, P.; Risaliti, G.; Saez, C.; Teng, S. H.; Walton, D. J.; Zhang, W. W.

    2013-01-01

    We present Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain approx. or equal to 400-600 hard X-ray (is greater than or equal to 10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed N(sub H) is less than or equal to 10(exp24) cm(exp-2). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain the column densities for both to be N(sub H) 7 × 10(exp 24) cm(exp-2) if the weak hard X-ray emission is caused by obscuration from the shielding gas. We discuss a few possibilities for how PG 1004+130 could have Compton-thick shielding gas without strong Fe Ka line emission; dilution from jet-linked X-ray emission is one likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place statistical constraints upon the fraction of intrinsically X-ray weak BAL quasars; this fraction is likely 17%-40%.

  20. GRB 090902B: afterglow observations and implications

    CERN Document Server

    Pandey, S B; Perley, D A; Guidorzi, C; Wiersema, K; Malesani, D; Akerlof, C; Ashley, M C B; Bersier, D; Cano, Z; Gomboc, A; Ilyin, I; Jakobsson, P; Kleiser, I K W; Kobayashi, S; Kouveliotou, C; Levan, A J; McKay, T A; Melandri, A; Mottram, C J; Mundell, C G; O'Brien, P T; Phillips, A; Rex, J M; Siegel, M H; Smith, R J; Steele, I A; Stratta, G; Tanvir, N R; Weights, D; Yost, S A; Yuan, F; Zheng, W

    2010-01-01

    The optical-infrared afterglow of the LAT-detected long duration burst, GRB 090902B, has been observed by several instruments. The earliest detection by ROTSE-IIIa occurred 80 minutes after detection by the GBM instrument onboard the Fermi Gamma-Ray Space Telescope, revealing a bright afterglow and a decay slope suggestive of a reverse shock origin. Subsequent optical-IR observations followed the light curve for 6.5 days. The temporal and spectral behavior at optical-infrared frequencies is consistent with synchrotron fireball model predictions; the cooling break lies between optical and XRT frequencies ~ 1.9 days after the burst. The inferred electron energy index is $p = 1.8 \\pm 0.2$, which would however imply an X-ray decay slope flatter than observed. The XRT and LAT data have similar spectral indices and the observed steeper value of the LAT temporal index is marginally consistent with the predicted temporal decay in the radiative regime of the forward shock model. Absence of a jet break during the first...

  1. Afterglow Radiation from Gamma Ray Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Desmond, Hugh; /Leuven U. /SLAC

    2006-08-28

    Gamma-ray bursts (GRB) are huge fluxes of gamma rays that appear randomly in the sky about once a day. It is now commonly accepted that GRBs are caused by a stellar object shooting off a powerful plasma jet along its rotation axis. After the initial outburst of gamma rays, a lower intensity radiation remains, called the afterglow. Using the data from a hydrodynamical numerical simulation that models the dynamics of the jet, we calculated the expected light curve of the afterglow radiation that would be observed on earth. We calculated the light curve and spectrum and compared them to the light curves and spectra predicted by two analytical models of the expansion of the jet (which are based on the Blandford and McKee solution of a relativistic isotropic expansion; see Sari's model [1] and Granot's model [2]). We found that the light curve did not decay as fast as predicted by Sari; the predictions by Granot were largely corroborated. Some results, however, did not match Granot's predictions, and more research is needed to explain these discrepancies.

  2. The Optical Afterglow of GRB 011211

    CERN Document Server

    Holland, S T; Gladders, M D; Barrientos, L F; Berlind, P; Bersier, D F; Garnavich, P M; Jha, S; Stanek, K Z; Holland, Stephen T.; Gladders, Michael D.; Bersier, David; Garnavich, Peter M.; Jha, Saurabh

    2002-01-01

    We present early-time optical photometry and spectroscopy of the optical afterglow of the gamma-ray burst GRB 011211. The spectrum contains several narrow metal lines which are consistent with the burst occurring at a redshift of 2.140 +/- 0.001. The optical afterglow decays as a power law with a slope of 0.83 +/- 0.04 for approximately the first two days after the burst at which time there is evidence for a break. The slope after the break is greater than approximately 1.4. There is evidence for rapid variations in the R-band light approximately 0.5 days after the burst, which suggests that there are density fluctuations near the GRB on spatial scales of approximately 30 to 200 AU. The magnitude of the break in the light curve, and the observed fluence, suggest that the burst expanded into an ambient medium that is homogeneous on large scales with a local particle density between approximately 0.1 and 10 per cubic cm. The total energy in the burst was 1.6-2.4 x 10^50 erg, consistent with the ``standard'' val...

  3. Coherent terahertz emission from Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} intrinsic Josephson junction stacks

    Energy Technology Data Exchange (ETDEWEB)

    Rudau, Fabian; Gross, Boris; Wieland, Raphael; Judd, Thomas; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut and Center for Collective Quantum Phenomena in LISA" +, Universitaet Tuebingen, Tuebingen (Germany); Kinev, Nickolay; Koshelets, Valery [Kotel' nikov Institute of Radio Engineering and Electronics, Moscow (Russian Federation); Tsujimoto, Manabu [Kyoto University, Kyoto (Japan); Ji, Min; Huang, Ya; Zhou, Xianjing; An, Deyue; Wang, Huabing [National Institute for Materials Science, Tsukuba (Japan); Research Institute of Superconductor Electronics, Nanjing University, Nanjing (China); Wu, Peiheng [Research Institute of Superconductor Electronics, Nanjing University, Nanjing (China); Hatano, Takeshi [National Institute for Materials Science, Tsukuba (Japan)

    2015-07-01

    Stacks of intrinsic Josephson junctions, made of the high temperature superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, are promising candidates to be used as generators of electromagnetic waves in the terahertz regime, in principle allowing frequencies up to ∝10 THz. Ranging from 0.4 to 1 THz, coherent emission was detected from large, rectangular stacks, producing several tens of microwatt in power. Despite of several years of research, the mechanism of synchronizing all the junctions in the stack is still not fully understood. We investigated the heat distribution and electromagnetic standing waves in such stacks, as well as the generation of terahertz radiation, using a combination of electric transport measurements, direct radiation detection and low temperature scanning laser microscopy. Recent experimental results from our collaboration will be presented and compared to numerical simulations.

  4. Discovery of Smoothly Evolving Blackbodies in the Early Afterglow of GRB 090618 : An Evidence for a Spine-Sheath Jet?

    CERN Document Server

    Basak, Rupal

    2014-01-01

    GRB~090618 is a bright GRB with multiple pulses. It shows evidence of a thermal emission in the initial pulses as well as in the early afterglow phase. We investigate the shape and evolution of the thermal component in the early afterglow/ late prompt emission phase using data from Swift/BAT, Swift/XRT, and Fermi/GBM detectors. An independent fit to the BAT and the XRT data reveals two correlated blackbodies with monotonically decreasing temperatures. Hence we investigated the combined data with a model consisting of two blackbodies and a power-law (2BBPL), a model suggested for several bright GRBs. We elicit the following interesting features of the 2BBPL model: a) the same model is applicable from the peak of the last pulse in the prompt emission to the afterglow emission, b) the ratio of temperatures and the fluxes of the two black bodies remain constant throughout the observations, c) the black body temperatures and fluxes show a monotonic decrease with time, with the fluxes dropping about a factor of two...

  5. The Remarkable Afterglow of GRB 061007: Implications for Optical Flashes and GRB Fireballs

    CERN Document Server

    Mundell, C G; Guidorzi, C; Kobayashi, S; Steele, I A; Malesani, D; Amati, L; D'Avanzo, P; Bersier, D F; Gomboc, A; Rol, E; Bode, M F; Carter, D; Mottram, C J; Monfardini, A; Smith, R J; Malhotra, S; Wang, J; Bannister, N; O'Brien, P T; Tanvir, N R

    2006-01-01

    We present a multiwavelength analysis of Swift GRB 061007. The 2-m robotic Faulkes Telescope South (FTS) began observing 137 s after the onset of the gamma-ray emission, when the optical counterpart was already decaying from R~10.3 mag, and continued observing for the next 5.5 hours. These observations begin during the final gamma-ray flare and continue through and beyond a long, soft tail of gamma-ray emission whose flux shows an underlying simple power law decay identical to that seen at optical and X-ray wavelengths, with temporal slope alpha~1.7. This remarkably simple decay in all of these bands is rare for Swift bursts, which often show much more complex light curves. We suggest the afterglow emission begins as early as 30-100 s and is contemporaneous with the on-going variable prompt emission from the central engine, but originates from a physically distinct region dominated by the forward shock. The afterglow continues unabated until at least ~10^5 seconds showing no evidence of a break. The observed ...

  6. Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data

    Energy Technology Data Exchange (ETDEWEB)

    Nousek, J.A.; Kouveliotou, C.; Grupe, D.; Page, K.; Granot, J.; Ramirez-Ruiz, E.; Patel, S.K.; Burrows, D.N.; Mangano, V.; Barthelmy, S.; Beardmore, A.P.; Campana, S.; Capalbi, M.; Chincarini, G.; Cusumano, G.; Falcone, A.D.; Gehrels, N.; Giommi, P.; Goad, M.; Godet, O.; Hurkett, C.; /Penn State U., Astron. Astrophys. /NASA, Marshall /Leicester

    2005-08-17

    We present new observations of the early X-ray afterglows of the first 27 gamma-ray bursts (GRBs) detected with the Swift X-ray Telescope (XRT). The early X-ray afterglows show a canonical behavior, where the light curve broadly consists of three distinct power law segments: (1) an initial very steep decay ({infinity} t{sup -a} with 3 {approx}< a{sub 1} {approx}< 5) , followed by (2) a very shallow decay (0.2 {approx}< a{sub 2} {approx}< 0.8), and finally (3) a somewhat steeper decay (1 {approx}< a{sub 3} {approx}< 1.5). These power law segments are separated by two corresponding break times, 300 s {approx}< t{sub break,1} {approx}< 500 s and 10{sup 3} s {approx}< t{sub break,2} {approx}< 10{sup 4} s. On top of this canonical behavior of the early X-ray light curve, many events have superimposed X-ray flares, which are most likely caused by internal shocks due to long lasting sporadic activity of the central engine, up to several hours after the GRB. We find that the initial steep decay is consistent with it being the tail of the prompt emission, from photons that are radiated at large angles relative to our line of sight. The first break in the light curve (t{sub break,1}) takes place when the forward shock emission becomes dominant, with the intermediate shallow flux decay (a{sub 2}) likely caused by the continuous energy injection into the external shock. When this energy injection stops, a second break is then observed in the light curve (t{sub break,2}). This energy injection increases the energy of the afterglow shock by at least a factor of f {approx}> 4, and augments the already severe requirements for the efficiency of the prompt gamma-ray emission.

  7. Modeling the Multi-band Afterglow of GRB 130831A: Evidence for a Spinning-down Magnetar Dominated by Gravitational Wave Losses?

    Science.gov (United States)

    Zhang, Q.; Huang, Y. F.; Zong, H. S.

    2016-06-01

    The X-ray afterglow of GRB 130831A shows an “internal plateau” with a decay slope of ˜0.8, followed by a steep drop at around 105 s with a slope of ˜6. After the drop, the X-ray afterglow continues with a much shallower decay. The optical afterglow exhibits two segments of plateaus separated by a luminous optical flare, followed by a normal decay with a slope basically consistent with that of the late-time X-ray afterglow. The decay of the internal X-ray plateau is much steeper than what we expect in the simplest magnetar model. We propose a scenario in which the magnetar undergoes gravitational-wave-driven r-mode instability, and the spin-down is dominated by gravitational wave losses up to the end of the steep plateau, so that such a relatively steep plateau can be interpreted as the internal emission of the magnetar wind and the sharp drop can be produced when the magnetar collapses into a black hole. This scenario also predicts an initial X-ray plateau lasting for hundreds of seconds with an approximately constant flux which is compatible with observation. Assuming that the magnetar wind has a negligible contribution in the optical band, we interpret the optical afterglow as the forward shock emission by invoking the energy injection from a continuously refreshed shock following the prompt emission phase. It is shown that our model can basically describe the temporal evolution of the multi-band afterglow of GRB 130831A.

  8. Gamma-Ray Bursts and Afterglows: a Multi-Wavelength Study in the Swift Era

    Science.gov (United States)

    Yu, Y. W.

    2010-01-01

    Gamma-ray bursts (GRBs), which are generally followed by long-lasting low-frequency afterglow emission, are short and intense pulses of gamma-rays observed from the sky in arbitrary directions. In order to observe the multi-wavelength emission at the early afterglow phase and even the prompt emission phase, NASA launched the Swift satellite on Nov. 20th 2004. Swift can localize GRBs within about 10 seconds. A brief review on the recent progress in observations and theories in the Swift era is given in Chapter 1. This paper focuses on the features of the early afterglows and the multi-wavelength prompt emission. In Chapters 2 and 3, we try to explain the shallow-decaying X-ray afterglows and X-ray flares, both of which are unaccountable in the standard afterglow model. (1) It is widely accepted that the shallow decay phase indicates a continuous energy injection into the GRB blast wave, and this energy could be released from the central engine after the burst. Based on the knowledge of the evolution of a pulsar wind, we argue that the injected flow interacting with the GRB blast wave is an ultra-relativistic kinetic-energy flow (i.e., wind) rather than pure electromagnetic waves. Therefore, a relativistic wind bubble (RWB) including a pair of shocks will be formed. Our numerical calculations and the fitting results show that the emission from an RWB can well account for the X-ray shallow decay phase. (2) For the X-ray flares that are attributed to some intermediate late activities of the central engine, we analyze the detailed dynamics of late internal shocks which directly produce the flare emission. Comparing the theoretical results with the lower limits of the observational luminosities and the profiles of the flare light curves, we find some constraints on the properties of the pre-collision shells, which are directly determined by the central object. In Chapter 4, we investigate the high-energy afterglow emission during the shallow decay phase in two models, i

  9. Nitrocarburizing treatments using flowing afterglow processes

    Science.gov (United States)

    Jaoul, C.; Belmonte, T.; Czerwiec, T.; David, N.

    2006-09-01

    Nitrocarburizing of pure iron samples is achieved at 853 K and is easily controlled by introducing C 3H 8 in the afterglow of a flowing microwave Ar-N 2-H 2 plasma. The carbon uptake in the solid is actually possible with methane but strongly limited. The use of propane enhances the carbon flux and the ɛ/α configuration is synthesized for the first time by this kind of process. For this stack, diffusion paths in the ternary system determined from chemical analyses by secondary neutral mass spectrometry reproduce satisfactorily X-ray diffraction results which only reveal, as optical micrographs, ɛ and α phases. Propane offers an accurate control of the nitrocarburizing conditions. As an example, a modulation of N and C contents in iron could be achieved to create new carbonitride multilayers.

  10. Nitrocarburizing treatments using flowing afterglow processes

    Energy Technology Data Exchange (ETDEWEB)

    Jaoul, C. [Laboratoire de Science et Genie des Surfaces (UMR CNRS 7570), Ecole des Mines, Parc de Saurupt, 54042 Nancy Cedex (France); Belmonte, T. [Laboratoire de Science et Genie des Surfaces (UMR CNRS 7570), Ecole des Mines, Parc de Saurupt, 54042 Nancy Cedex (France)]. E-mail: Thierry.Belmonte@mines.inpl-nancy.fr; Czerwiec, T. [Laboratoire de Science et Genie des Surfaces (UMR CNRS 7570), Ecole des Mines, Parc de Saurupt, 54042 Nancy Cedex (France); David, N. [Laboratoire de Chimie du Solide Mineral, Universite Henri Poincare Nancy-I, Vandoeuvre-Les-Nancy (France)

    2006-09-30

    Nitrocarburizing of pure iron samples is achieved at 853 K and is easily controlled by introducing C{sub 3}H{sub 8} in the afterglow of a flowing microwave Ar-N{sub 2}-H{sub 2} plasma. The carbon uptake in the solid is actually possible with methane but strongly limited. The use of propane enhances the carbon flux and the {epsilon}/{alpha} configuration is synthesized for the first time by this kind of process. For this stack, diffusion paths in the ternary system determined from chemical analyses by secondary neutral mass spectrometry reproduce satisfactorily X-ray diffraction results which only reveal, as optical micrographs, {epsilon} and {alpha} phases. Propane offers an accurate control of the nitrocarburizing conditions. As an example, a modulation of N and C contents in iron could be achieved to create new carbonitride multilayers.

  11. Decay phases of Swift X-ray afterglows and the forward-shock model.

    Science.gov (United States)

    Panaitescu, A

    2007-05-15

    The X-ray flux of the gamma-ray burst (GRB) afterglows monitored by the Swift satellite from January 2005 to July 2006 displays one to four phases of flux power-law decay. In chronological order, they are: the GRB tail, the 'hump', the standard decay and the post-jet-break decay. More than half of the GRB tails can be identified with the large-angle emission produced during the burst (but arriving later at observer). The remaining, slower GRB tails imply that the gamma-ray mechanism continues to radiate after the burst, as also suggested by the frequent occurrence of X-ray flares during the burst tail. The several GRB tails exhibiting a slow unbroken power-law decay until 100ks must be attributed to the forward shock. In fact, the decay of most GRB tails is also consistent with that of the forward-shock emission from a narrow jet. The X-ray light-curve hump may be due to an increase of the kinetic energy per solid angle of the forward-shock region visible to the observer, caused by either the transfer of energy from ejecta to the forward shock or the emergence of the emission from an outflow seen from a location outside the jet opening. The decay following the X-ray light-curve hump is consistent with the emission from an adiabatic blast wave but, contrary to expectations, the light-curve decay index and spectral slope during this phase are not correlated. The X-ray light curves of two dozens X-ray afterglows that followed for more than a week do not exhibit a jet break, in contrast with the behaviour of pre-Swift optical afterglows, which displayed jet breaks at 0.5-2 days. Nevertheless, the X-ray light curves of several Swift afterglows show a second steepening break at 0.4-3 days that is consistent with the break expected for a jet when its edge becomes visible to the observer.

  12. Near Band Edge Emission by Free Exciton Decay and Intrinsic Ferromagnetic Ordering of Cu-Doped SnO2 Hollow Nanofibers.

    Science.gov (United States)

    Mohanapriya, P; Jaya, N Victor

    2015-03-01

    High quality nanocrystalline pristine and Cu-doped SnO2 hollow nanofibers were successfully prepared through simple and effective electrospinning technique. Nanofibers calcined at 600 °C for 3 h were characterized with different analytical techniques such as X-ray diffraction (XRD), Transmission electron Microscope (TEM) and Vibrating sample magnetometer (VSM). Observed TEM images and XRD patterns were corroborate to the formation of tetragonal crystalline SnO2 hollow nanofibers with rutile phase. Excellent optical behaviour was observed for Cu-doped SnO2. Highly intense near band edge emission at 3.58 eV for Cu-doped SnO2 evidences the free exciton decay process in the hollow nanofibers. For the first time we have reported here the near band edge PL emission in Cu-doped SnO2 tubular hollow nanostructure. This study substantiates that material potential for UV-lasing application. In addition to the above, magnetic measurement ascribes that Cu-doped SnO2 exhibit the intrinsic room temperature ferromagnetism within the low field strength. The occurrence of ferromagnetism in Cu-doped SnO2 is directly related to the p-d ferromagnetic exchange coupling between the local magnetic moment of Cu2+ and the polarized valence electrons of surrounding oxygen. Over all this study provides the primary information about tunable multifunctionality of SnO2 hollow nanostructures by adding the non-magnetic Cu ions.

  13. Coherent emission of terahertz radiation from intrinsic Josephson junctions in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Rudau, Fabian; Wieland, Raphael; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universitaet Tuebingen (Germany); Zhou, Xianjing; Ji, Min; Hao, Luyao; Huang, Ya; Wang, Huabing [Research Institute of Superconductor Electronics, Nanjing University (China); National Institute for Materials Science, Tsukuba (Japan); Kinev, Nickolay; Koshelets, Valery [Kotel' nikov Institute of Radio Engineering and Electronics, Moscow (Russian Federation); Li, Jun; Wu, Peiheng [Research Institute of Superconductor Electronics, Nanjing University (China); Hatano, Takeshi [National Institute for Materials Science, Tsukuba (Japan)

    2016-07-01

    Stacks of intrinsic Josephson junctions, made of the high-T{sub c} superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, can be used as emitters of electromagnetic waves at terahertz frequencies. Coherent emission from 0.3 to 2.4 THz was detected from large, rectangular or disc-shaped mesa structures. Having a linewidth of only a few MHz, emission powers of several tens of microwatt can be produced for single stacks and up to 0.61 mW for an array of mesas. Since the mechanisms of synchronizing all the junctions in the stack is still not fully understood, we investigated the temperature distribution and electromagnetic standing waves in such stacks, as well as the generation of terahertz radiation, using a combination of electric transport measurements, direct radiation detection and low temperature scanning laser microscopy. Recent experimental results from our collaboration will be presented and compared to numerical simulations.

  14. Three-Dimensional Simulations of the Electrothermal and Terahertz Emission Properties of Bi2 Sr2 CaCu2 O8 Intrinsic Josephson Junction Stacks

    Science.gov (United States)

    Rudau, F.; Wieland, R.; Langer, J.; Zhou, X. J.; Ji, M.; Kinev, N.; Hao, L. Y.; Huang, Y.; Li, J.; Wu, P. H.; Hatano, T.; Koshelets, V. P.; Wang, H. B.; Koelle, D.; Kleiner, R.

    2016-04-01

    We use 2D coupled sine-Gordon equations combined with 3D heat diffusion equations to numerically investigate the thermal and electromagnetic properties of a 250 ×70 μ m2 intrinsic Josephson junction stack. The 700 junctions are grouped to 20 segments; we assume that in a segment all junctions behave identically. At large input power, a hot spot forms in the stack. Resonant electromagnetic modes oscillating either along the length [(0, n ) modes] or the width [(m , 0) modes] of the stack or having a more complex structure can be excited both with and without a hot spot. At fixed bath temperature and bias current, several cavity modes can coexist in the absence of a magnetic field. The (1, 0) mode considered to be the most favorable mode for terahertz emission can be stabilized by applying a small magnetic field along the length of the stack. A strong field-induced enhancement of the emission power is also found in experiment for an applied field around 5.9 mT.

  15. X-Ray Lines and Absorption Edges in GRBs and Their Afterglows

    CERN Document Server

    Böttcher, M

    2002-01-01

    Absorption and Reprocessing of Gamma-ray burst radiation in the environment of cosmological GRBs can be used as a powerful probe of the elusive nature of their progenitors. In particular, transient X-ray emission line and absorption features in the prompt and early afterglows of GRBs are sensitive to details of the location and density structure of the reprocessing and/or absorbing material. To date, there have been only rather few detections of such features, and the significance is marginal in most individual cases. However, transient X-ray emission lines in GRB afterglows have now been found by four different X-ray satellites, which may justify a more detailed theoretical investigation of their origin. In this paper, I will first present a brief review of the status of observations of transient X-ray emission line and absorption features. I will then discuss general physics constraints which those results impose on isotropy, homogeneity, and location of the reprocessing material with respect to the GRB sou...

  16. Influence on the long afterglow properties by the environmental temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wu Haoyi [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Hu Yihua, E-mail: huyh@gdut.edu.c [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Wang Yinhai; Mou Zhongfei [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2010-01-15

    Sr{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+}, Dy{sup 3+} (SMED) and Ba{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+}, Dy{sup 3+} (BMED) were synthesized with the solid-state reaction. The SMED shows long afterglow while the afterglow of BMED is not visible at room temperature. When the environmental temperature is 150 deg. C, the afterglow of SMED is not obvious while the BMED shows the long afterglow. The decay curves measured at different temperatures conform to this phenomenon. It ascribes to the different trap depths of different samples. The thermoluminescence (TL) curves of SMED peaks at 80 deg. C. BMED has two TL peaks peaking at about 80 and 175 deg. C respectively. The low temperature peak is weak and its density is small. The high-temperature peak reveals that one trap of BMED is deeper than the one of SMED. The afterglows of the phosphors strongly depend on the environmental temperature since the lifetime of the trapping carriers is temperature-dependence. BMED is a potential optimum long afterglow phosphor for the purpose of high-temperature application.

  17. The Supercritical Pile Gamma-Ray Burst Model: The GRB Afterglow Steep Decline and Plateau Phase

    Science.gov (United States)

    Sultana, Joseph; Kazanas, D.; Mastichiadis, A.

    2013-01-01

    We present a process that accounts for the steep decline and plateau phase of the Swift X-Ray Telescope (XRT) light curves, vexing features of gamma-ray burst (GRB) phenomenology. This process is an integral part of the "supercritical pile" GRB model, proposed a few years ago to account for the conversion of the GRB kinetic energy into radiation with a spectral peak at E(sub pk) is approx. m(sub e)C(exp 2). We compute the evolution of the relativistic blast wave (RBW) Lorentz factor Gamma to show that the radiation-reaction force due to the GRB emission can produce an abrupt, small (approx. 25%) decrease in Gamma at a radius that is smaller (depending on conditions) than the deceleration radius R(sub D). Because of this reduction, the kinematic criticality criterion of the "supercritical pile" is no longer fulfilled. Transfer of the proton energy into electrons ceases and the GRB enters abruptly the afterglow phase at a luminosity smaller by approx. m(sub p)/m(sub e) than that of the prompt emission. If the radius at which this slow-down occurs is significantly smaller than R(sub D), the RBW internal energy continues to drive the RBW expansion at a constant (new) Gamma and its X-ray luminosity remains constant until R(sub D) is reached, at which point it resumes its more conventional decay, thereby completing the "unexpected" XRT light curve phase. If this transition occurs at R is approx. equal to R(sub D), the steep decline is followed by a flux decrease instead of a "plateau," consistent with the conventional afterglow declines. Besides providing an account of these peculiarities, the model suggests that the afterglow phase may in fact begin before the RBW reaches R is approx. equal to R(sub D), thus providing novel insights into GRB phenomenology.

  18. The supercritical pile gamma-ray burst model: The GRB afterglow steep decline and plateau phase

    Energy Technology Data Exchange (ETDEWEB)

    Sultana, J. [Mathematics Department, Faculty of Science, University of Malta, Msida MSD2080 (Malta); Kazanas, D. [Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Mastichiadis, A., E-mail: joseph.sultana@um.edu.mt [Department of Physics, University of Athens, Panepistimiopolis, GR 15783 Zografos (Greece)

    2013-12-10

    We present a process that accounts for the steep decline and plateau phase of the Swift X-Ray Telescope (XRT) light curves, vexing features of gamma-ray burst (GRB) phenomenology. This process is an integral part of the 'supercritical pile' GRB model, proposed a few years ago to account for the conversion of the GRB kinetic energy into radiation with a spectral peak at E {sub pk} ∼ m{sub e}c {sup 2}. We compute the evolution of the relativistic blast wave (RBW) Lorentz factor Γ to show that the radiation-reaction force due to the GRB emission can produce an abrupt, small (∼25%) decrease in Γ at a radius that is smaller (depending on conditions) than the deceleration radius R{sub D} . Because of this reduction, the kinematic criticality criterion of the 'supercritical pile' is no longer fulfilled. Transfer of the proton energy into electrons ceases and the GRB enters abruptly the afterglow phase at a luminosity smaller by ∼m{sub p} /m{sub e} than that of the prompt emission. If the radius at which this slow-down occurs is significantly smaller than R{sub D} , the RBW internal energy continues to drive the RBW expansion at a constant (new) Γ and its X-ray luminosity remains constant until R{sub D} is reached, at which point it resumes its more conventional decay, thereby completing the 'unexpected' XRT light curve phase. If this transition occurs at R ≅ R{sub D} , the steep decline is followed by a flux decrease instead of a 'plateau,' consistent with the conventional afterglow declines. Besides providing an account of these peculiarities, the model suggests that the afterglow phase may in fact begin before the RBW reaches R ≅ R{sub D} , thus providing novel insights into GRB phenomenology.

  19. Very Early Optical Afterglows for Geometric Models of X-ray Flashes and X-ray Rich GRBs

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    If X-ray flashes (XRFs) and X-ray rich Gamma-ray Bursts (XRRGs) have the same origin as the Gamma-ray bursts (GRBs) but are viewed off-center from structured jets, their early afterglows may differ from those of GRBs, and when the ultra-relativistic outflow interacts with the surrounding medium, there are two shocks formed, a forward shock (FS), and a reverse shock (RS). We calculate numerically the early afterglow powered by uniform jets, Gaussian jets and power-law jets in the forward-reverse shock scenario. A set of differential equations govern the dynamical evolution. The synchrotron self-Compton effect has been taken into account in the calculation. In the uniform jets, the very early afterglows of XRRGs and XRFs are significantly lower than the GRBs and the observed peak times of RS emission are later in the interstellar medium environment. The RS components in XRRGs and XRFs are difficult to detect, but in the stellar wind environment, the reduction of the very early flux and the delay of the RS peak time are not so remarkable. In nonuniform jets (Gaussian and power-law jets), where there are emission materials on the line of sight, the very early light curve resembles equivalent isotropic ejecta in general although the RS flux decay index shows notable deviations if the RS is relativistic (in stellar wind).

  20. SrAl2O4 :Eu2+, Dy3+ Long Afterglow Phosphors Prepared by Chemical Coprecipitation Method

    Institute of Scientific and Technical Information of China (English)

    Sun Yanbin; Qiu Guanming; Zhang Shengqu; Zhang Ming; Yan Changhao; Dai Shaojun

    2004-01-01

    SrAl2 O4: Eu2+ , Dy3+ long afterglow phosphors were prepared by chemical coprecipitation method. Ammonium carbonate and ammonium hydrogen carbonate were used as the precipitants. The preparation of the SrAl2 O4: Eu2+ ,Dy3 + precursor was completed at room temperature by controlling the concentration of the metal-salt solution, pH value of the system, etc. The phosphors were prepared by sintering the precursor at 1000 ~ 1200 ℃ in a weak reducing atmosphere for 2 h. The XRD, SEM, excitation spectra, emission spectra and afterglow decay of the samples were tested and the optimal synthesis conditions of the SrAl2O4: Eu2+ , Dy3+ long afterglow phosphors prepared by precipitation method were determined. The phosphor which had good luminescent properties is prepared and its persistent time can reach more than 1600 min. In the coprecipitation process, a small amount of glucose operates to refe the luminescent powders. The particle size of the phosphor can be less than 1 μm. The sintering temperature of the sample prepared by the coprecipitation method is much lower than that of the one prepared by the high temperature solid state method.Compared with the high temperature solid state method, a clear blue shift occurs in the excitation and emission spectra of the samples.

  1. Swift and Suzaku Observations of the X-Ray Afterglow from the GRB 060105

    CERN Document Server

    Tashiro, M S; Angelini, L; Barthelmy, S; Gehrels, N; Ishikawa, N; Kaluzienski, L J; Kawai, N; Kelley, R L; Kinugasa, K; Kodaira, H; Kohmura, T; Kubota, K; Maeda, Y; Maeno, S; Murakami, H; Murakami, T; Nakagawa, Y E; Nakazawa, K; Nousek, J; Okuno, S; Onda, K; Reeves, J N; Ricker, G; Sato, G; Sonoda, E; Suzuki, M; Takahashi, T; Tamagawa, T; Torii, K; Ueda, Y; Urata, Y; Yamaoka, K; Yamauchi, M; Yonetoku, D; Yoshida, A; Yoshinari, S

    2006-01-01

    Results are presented of early X-ray afterglow observations of GRB 060105 by Swift and Suzaku. The bright, long gamma-ray burst GRB 060105 triggered the Swift Burst Alert Telescope (BAT) at 06:49:28 on 5 January 2006. The Suzaku team commenced a pre-planned target of opportunity observation at 19 ks (5.3 hr) after the Swift trigger. Following the prompt emission and successive very steep decay, a shallow decay was observed from T_0+187 s to T_0+1287 s. After an observation gap during T_0 +(1.5-3) ks, an extremely early steep decay was observed in T_0+(4-30) ks. The lightcurve flattened again at T_0+30 ks, and another steep decay followed from T_0+50 ks to the end of observations. Both steep decays exhibited decay indices of 2.3 - 2.4. This very early break, if it is a jet break, is the earliest case among X-ray afterglow observations, suggesting a very narrow jet whose opening angle is well below 1 degree. The unique Suzaku/XIS data allow us to set very tight upper limits on line emission or absorption in thi...

  2. Diagnostics of plasma decay and afterglow transient of an electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Tarvainen, O; Ropponen, T; Toivanen, V; Kalvas, T; Arje, J; Koivisto, H, E-mail: olli.tarvainen@jyu.f [University of Jyvaeskylae, Department of Physics, Accelerator Laboratory PO Box 35 (YFL), 40500 Jyvaeskylae (Finland)

    2010-08-15

    The electron cyclotron resonance ion sources at the JYFL (University of Jyvaeskylae, Department of Physics) accelerator laboratory have been operated in pulsed mode to study the decay of bremsstrahlung emission and ion beam currents of different charge states. The purpose of the experiments is to gain understanding on the ion source parameters affecting the afterglow. It was observed that the bremsstrahlung emission characteristics during the afterglow and decay times of extracted ion beam currents are virtually independent of the ion source tuning parameters. The decay time of different charge states was found to be almost inversely proportional to the square of the ion charge. The result is in good agreement with a simple theoretical model based on diffusion of ions from the magnetic field of the ion source. It was observed that the plasma decay time is shorter in the case of the ion source with lower operation frequency and, thus, lower magnetic field strength. The scaling between the ion sources supports a model based on Bohm diffusion, arising from non-linear effects such as instabilities and fluctuating fields in turbulent plasma. The experiments provide information on the mechanisms causing instabilities during the plasma decay.

  3. Weak Hard X-ray Emission from Two Broad Absorption Line Quasars Observed with NuSTAR: Compton-thick Absorption or Intrinsic X-ray Weakness?

    CERN Document Server

    Luo, B; Alexander, D M; Harrison, F A; Stern, D; Bauer, F E; Boggs, S E; Christensen, F E; Comastri, A; Craig, W W; Fabian, A C; Farrah, D; Fiore, F; Fuerst, F; Grefenstette, B W; Hailey, C J; Hickox, R; Madsen, K K; Matt, G; Ogle, P; Risaliti, G; Saez, C; Teng, S H; Walton, D J; Zhang, W W

    2013-01-01

    We present NuSTAR hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain ~400-600 hard X-ray (>10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed (NH<1E24 cm^{-2}). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain the column densities for both to be NH~7E24 cm^{-2} if the weak hard X-ray emission is caused by obscuration from the shielding gas. We d...

  4. Simulations of GRB Jets in a Stratified External Medium: Dynamics, Afterglow Lightcurves, Jet Breaks and Radio Calorimetry

    CERN Document Server

    De Colle, Fabio; Granot, Jonathan; Lopez-Camara, Diego

    2011-01-01

    The dynamics of GRB jets during the afterglow phase is most reliably and accurately modelled using hydrodynamic simulations. All published simulations, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with $\\rho \\propto r^{-k}$ for k = 0, 1, 2. The simulations are performed in 2D using the special relativistic version of the Mezcal code. The dynamics for stratified external media are broadly similar to those derived for expansion into a uniform external medium. The jet half-opening angle start increasing logarithmically with time once the Lorentz factor drops below 1/theta_0. For larger k values the lateral expansion is faster at early times and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timesc...

  5. The red optical afterglow of GRB 030725

    CERN Document Server

    Pugliese, G; Gorosabel, J; Jensen, B L; Fynbo, J P U; Hjorth, J; Jorgensen, S F; Monard, B; Vinter, C

    2005-01-01

    We present a photometric study of the optical counterpart of the long-duration Gamma Ray Burst (GRB) 030725, which triggered the HETE FREGATE and WXM instruments on July 25th, 2003, and lasted more than 160s. An optical counterpart was identified at the Bronberg Observatory in South Africa about 7 hours after the burst occurred. The optical afterglow (OA) was observed between 4 and 15 days after the burst with the 1.54m Danish telescope at La Silla in the V, Rc, and Ic bands. We fit a broken power law to the data and determine a break time in the light curve between 16 hours and 4.7 days after the first detection of the burst. The decay slope is alpha1 = -0.59 +0.59/-0.44 before and alpha2 = -1.43 +/- 0.06 after the break. A bump may be present in the light curve, only significant at the 2-sigma level, 13.9 days after the main burst. The spectral slope of the OA, measured 12 days after the burst, is -2.9 +/- 0.6 , i.e. it falls in the extreme red end of the distribution of previous OA spectral slopes. Observa...

  6. Homogeneous gas phase models of relaxation kinetics in neon afterglow

    Directory of Open Access Journals (Sweden)

    Marković Vidosav Lj.

    2007-01-01

    Full Text Available The homogeneous gas phase models of relaxation kinetics (application of the gas phase effective coefficients to represent surface losses are applied for the study of charged and neutral active particles decay in neon afterglow. The experimental data obtained by the breakdown time delay measurements as a function of the relaxation time td (τ (memory curve is modeled in early, as well as in late afterglow. The number density decay of metastable states can explain neither the early, nor the late afterglow kinetics (memory effect, because their effective lifetimes are of the order of milliseconds and are determined by numerous collision quenching processes. The afterglow kinetics up to hundreds of milliseconds is dominated by the decay of molecular neon Ne2 + and nitrogen ions N2 + (present as impurities and the approximate value of N2 + ambipolar diffusion coefficient is determined. After the charged particle decay, the secondary emitted electrons from the surface catalyzed excitation of nitrogen atoms on the cathode determine the breakdown time delay down to the cosmic rays and natural radioactivity level. Due to the neglecting of number density spatial profiles, the homogeneous gas phase models give only the approximate values of the corresponding coefficients, but reproduce correctly other characteristics of afterglow kinetics from simple fits to the experimental data.

  7. The γ-ray afterglows of tidal disruption events

    Science.gov (United States)

    Chen, Xian; Gómez-Vargas, Germán Arturo; Guillochon, James

    2016-05-01

    A star wandering too close to a supermassive black hole (SMBH) will be tidally disrupted. Previous studies of such `tidal disruption event' (TDE) mostly focus on the stellar debris that are bound to the system, because they give rise to luminous flares. On the other hand, half of the stellar debris in principle are unbound and can stream to a great distance, but so far there is no clear evidence that this `unbound debris stream' (UDS) exists. Motivated by the fact that the circum-nuclear region around SMBHs is usually filled with dense molecular clouds (MCs), here we investigate the observational signatures resulting from the collision between an UDS and an MC, which is likely to happen hundreds of years after a TDE. We focus on γ-ray emission (0.1-105 GeV), which comes from the encounter of shock-accelerated cosmic rays with background protons and, more importantly, is not subject to extinction. We show that because of the high proton density inside an MC, the peak γ-ray luminosity, about 1039 erg s-1, is at least 100 times greater than that in the case without an MC (only with a smooth interstellar medium). The luminosity decays on a time-scale of decades, depending on the distance of the MC, and about a dozen of these `TDE afterglows' could be detected within a distance of about 16 Mpc by the future Cherenkov Telescope Array. Without careful discrimination, these sources potentially could contaminate the searches for starburst galaxies, galactic nuclei containing millisecond pulsars or dark matter annihilation signals.

  8. Synthesis of Long Afterglow Phosphors MAl2O4:Eu2+, Dy3+(M=Ca, Sr, Ba) by Microemulsion Method and Their Luminescent Properties

    Institute of Scientific and Technical Information of China (English)

    Qiu Guanming; Chen Yongjie; Geng Xiujuan; Xiao Linjiu; Tian Yiguang; Sun Yanbin

    2005-01-01

    Long afterglow phosphors MAl2O4:Eu2+, Dy3+ (M=Ca, Sr, Ba) were synthesized by microemulsion method, and their crystal structure and luminescent properties were compared and investigated. XRD patterns of samples indicate that phosphors CaAl2O4:Eu2+, Dy3+ and SrAl2O4:Eu2+, Dy3+ are with monoclinic crystal structure and phosphor BaAl2O4:Eu2+, Dy3+ is with hexagonal crystal structure. The wide range of excitation spectrum of phosphors MAl2O4:Eu2+, Dy3+ (M=Ca,Sr,Ba) indicates that the luminescent materials can be excited by light from ultraviolet ray to visible light and the maximum emission wavelength of phosphors MAl2O4:Eu2+, Dy3+ (M=Ca, Sr, Ba) is found mainly at λem of 440 nm (M=Ca), 520 nm (M=Sr) and 496 nm (M=Ba) respectively, the corresponding colors of emission light are blue, green and cyna-green respectively. The afterglow decay tendency of phosphors can be summarized as three processes: initial rapid decay, intermediate transitional decay and very long slow decay. Afterglow decay curves coincide with formula I=At-n, and the sequence of afterglow intensity and time is Sr>Ca>Ba.

  9. Circular polarization in the optical afterglow of GRB 121024A

    CERN Document Server

    Wiersema, K; Toma, K; van der Horst, A J; Varela, K; Min, M; Greiner, J; Starling, R L C; Tanvir, N R; Wijers, R A M J; Campana, S; Curran, P A; Fan, Y; Fynbo, J P U; Gorosabel, J; Gomboc, A; Gotz, D; Hjorth, J; Jin, Z P; Kobayashi, S; Kouveliotou, C; Mundell, C; O'Brien, P T; Pian, E; Rowlinson, A; Russell, D M; Salvaterra, R; Alighieri, S di Serego; Tagliaferri, G; Vergani, S D; Elliott, J; Farina, C; Hartoog, O E; Karjalainen, R; Klose, S; Knust, F; Levan, A J; Schady, P; Sudilovski, V; Willingale, R

    2014-01-01

    Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet, when measured minutes after the burst, and the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after burst in GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and negligable circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blastwave. Here we report the detection of circularly polarized optical light in the afterglow of GRB 121024A, measured 0.1...

  10. GRB-081029: A Step Towards Understanding Multiple Afterglow Components

    Science.gov (United States)

    Holland Stephen T.

    2010-01-01

    We present an analysis of the unusual optical light curve of the gamma-ray burst-081029 at a redshift of z = 3.8474. We combine X-ray and optical observations from (Swift) with optical and infrared data from REM to obtain a detailed data set extending from approx 10(exp 2)s to approx 10(exp 5)s after the BAT trigger, and from approx.10 keV to 16,000 AA. The X-ray afterglow showed a shallow initial decay followed by u rapid decay after about 18,000 s. The optical afterglow, however, shows an uncharecteristic rise at about 5000 s that has no corresponding feature in the X-ray light curve. The data are not consistent with a single-component jet. It is possible that there are multiple physical components contributing to the afterglow of GRB-081029.

  11. Afterglow Light Curves and Broken Power Laws: A Statistical Study

    CERN Document Server

    J'ohannesson, G; Gudmundsson, E H; J\\'ohannesson, Gudlaugur; Bj\\"ornsson, Gunnlaugur; Gudmundsson, Einar H.

    2006-01-01

    In gamma-ray burst research it is quite common to fit the afterglow light curves with a broken power law to interpret the data. We apply this method to a computer simulated population of afterglows and find systematic differences between the known model parameters of the population and the ones derived from the power law fits. In general, the slope of the electron energy distribution is overestimated from the pre-break light curve slope while being underestimated from the post-break slope. We also find that the jet opening angle derived from the fits is overestimated in narrow jets and underestimated in wider ones. Results from fitting afterglow light curves with broken power laws must therefore be interpreted with caution since the uncertainties in the derived parameters might be larger than estimated from the fit. This may have implications for Hubble diagrams constructed using gamma-ray burst data.

  12. A Search for Discrete X-Ray Spectral Features in a Sample of Bright Gamma-Ray Burst Afterglows

    Energy Technology Data Exchange (ETDEWEB)

    Sako, M

    2004-09-09

    We present uniform, detailed spectral analyses of gamma-ray burst (GRB) X-ray afterglows observed with ASCA, Beppo-SAX, Chandra, and XMM-Newton, and critically evaluate the statistical significances of X-ray emission and absorption features in these spectra. The sample consists of 21 X-ray afterglow observations up to and including that of GRB040106 with spectra of sufficient statistical quality to allow meaningful line searches, chosen here somewhat arbitrarily to be detections with more than 100 total (source plus background) counts. This sample includes all nine X-ray afterglows with published claims of line detections. Moderate resolution spectra are available for 16 of the 21 sources, and for the remaining five the Chandra transmission grating spectrometers obtained high-resolution data. All of the data are available from the public archive. We test a simple hypothesis in which the observed spectra are produced by a power-law continuum model modified by photoelectric absorption by neutral material both in our Galaxy and possibly also local to the burst. As a sample, these afterglow spectra are consistent with this relatively simple model. However, since the {chi}{sup 2} statistic is not sensitive to weak and/or localized fluctuations, we have performed Monte Carlo simulations to search for discrete features and to estimate their significances. Our analysis shows that there are four afterglows (GRB011211, GRB030227, GRB021004, and GRB040106) with line-like features that are significant at the 3 {sigma} level. We cautiously note that, in two cases, the features are associated with an unusual background feature; in the other two, the fractional magnitudes of the lines are small, and comparable to the expected level of systematic uncertainty in the spectral response. In addition, none of the statistically significant features are seen in more than one detector or spectral order where available. We conclude that, to date, no credible X-ray line feature has been

  13. Dy{sup 3+}:Ca{sub 2}SnO{sub 4}, a new yellow phosphor with afterglow behavior

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Mingming; Zhang, Dongyun, E-mail: dyz@sit.edu.cn; Chang, Chengkang

    2015-08-05

    Highlights: • The photoluminescence and afterglow behavior of Dy{sup 3+}:Ca{sub 2}SnO{sub 4} was investigated. • PL spectra revealed the {sup 4}F{sub 9/2} → {sup 6}H{sub J} (J = 15/2, 13/2, 11/2) energy transition of Dy{sup 3+} ions in Ca{sub 2}SnO{sub 4}. • CIE chromaticity coordinates results confirmed a yellow light emitting of the Dy{sup 3+}:Ca{sub 2}SnO{sub 4}. • After the UV source was turned off, the Dy{sup 3+}:Ca{sub 2}SnO{sub 4} showed typical afterglow behavior. • The afterglow behavior of Dy{sup 3+}:Ca{sub 2}SnO{sub 4} was attributed to suitable electron and hole traps. - Abstract: This paper reports the photoluminescence and afterglow behavior of Dy{sup 3+} in Ca{sub 2}SnO{sub 4} matrix (Dy{sup 3+}:Ca{sub 2}SnO{sub 4}) prepared via a solid-state reaction. X-ray diffraction (XRD), photo luminescence spectroscope (PLS) and thermal luminescence spectroscope (TLS) were performed to investigate the physical properties of the phosphors. Typical {sup 4}F{sub 9/2} to {sup 6}H{sub j} energy transition of Dy{sup 3+} ions was detected by PL spectra. CIE chromaticity coordinates of x = 0.4319, y = 4.456, calculated from the emission spectra, confirmed a yellow light emitting of the Dy{sup 3+}:Ca{sub 2}SnO{sub 4} phosphors. The Ca{sub 2}SnO{sub 4} phosphors showed a typical afterglow behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of Dy{sup 3+}:Ca{sub 2}SnO{sub 4} phosphors was generated by the suitable electron or hole traps which was resulted from the doping the Ca{sub 2}SnO{sub 4} host with rare-earth ions (Dy{sup 3+})

  14. Modeling the early afterglow in the short and hard GRB 090510

    CERN Document Server

    Fraija, Nissim; Veres, Peter; Duran, Rodolfo Barniol

    2016-01-01

    The bright, short and hard GRB 090510 was detected by all instruments aboard Fermi and Swift satellites. The multiwavelength observations of this burst presented similar features with the Fermi-LAT-detected gamma-ray bursts. In the framework of the external shock model of early afterglow, a leptonic scenario that evolves in a homogeneous medium is proposed to revisit GRB 090510 and explain the multiwavelength light curve observations presented in this burst. These observations are consistent with the evolution of a jet before and after the jet break. The long-lasting LAT, X-ray and optical fluxes are explained in the synchrotron emission from the adiabatic forward shock. Synchrotron self-Compton emission from the reverse shock is consistent with the bright LAT peak provided that progenitor environment is entrained with strong magnetic fields. It could provide compelling evidence of magnetic field amplification in the neutron star merger.

  15. Modeling the Early Afterglow in the Short and Hard GRB 090510

    Science.gov (United States)

    Fraija, N.; Lee, W. H.; Veres, P.; Barniol Duran, R.

    2016-11-01

    The bright, short, and hard GRB 090510 was detected by all instruments aboard the Fermi and Swift satellites. The multiwavelength observations of this burst presented similar features to the Fermi-LAT-detected gamma-ray bursts. In the framework of the external shock model of early afterglow, a leptonic scenario that evolves in a homogeneous medium is proposed to revisit GRB 090510 and explain the multiwavelength light curve observations presented in this burst. These observations are consistent with the evolution of a jet before and after the jet break. The long-lasting LAT, X-ray, and optical fluxes are explained in the synchrotron emission from the adiabatic forward shock. Synchrotron self-Compton emission from the reverse shock is consistent with the bright LAT peak provided that the progenitor environment is entrained with strong magnetic fields. It could provide compelling evidence of magnetic field amplification in the neutron star merger.

  16. A new era of sub-millimeter GRB afterglow follow-ups with the Greenland Telescope

    CERN Document Server

    Urata, Yuji; Asada, Keiichi; Hirashita, Hiroyuki; Inoue, Makoto; Ho, Paul T P

    2015-01-01

    A planned rapid submillimeter (submm) Gamma Ray Burst (GRBs) follow-up observations conducted using the Greenland Telescope (GLT) is presented. The GLT is a 12-m submm telescope to be located at the top of the Greenland ice sheet, where the high-altitude and dry weather porvides excellent conditions for observations at submm wavelengths. With its combination of wavelength window and rapid responding system, the GLT will explore new insights on GRBs. Summarizing the current achievements of submm GRB follow-ups, we identify the following three scientific goals regarding GRBs: (1) systematic detection of bright submm emissions originating from reverse shock (RS) in the early afterglow phase, (2) characterization of forward shock and RS emissions by capturing their peak flux and frequencies and performing continuous monitoring, and (3) detections of GRBs as a result of the explosion of first-generation stars result of GRBs at a high redshift through systematic rapid follow ups. The light curves and spectra calcul...

  17. The unusual X-ray light-curve of GRB 080307: the onset of the afterglow?

    CERN Document Server

    Page, K L; O'Brien, P T; Tanvir, N R; Osborne, J P; Zhang, B; Holland, S T; Levan, A J; Melandri, A; Starling, R L C; Bersier, D; Burrows, D N; Geach, J E; Maxted, P

    2009-01-01

    Swift-detected GRB 080307 showed an unusual smooth rise in its X-ray light-curve around 100 seconds after the burst, at the start of which the emission briefly softened. This `hump' has a longer duration than is normal for a flare at early times and does not demonstrate a typical flare profile. Using a two component power-law-to-exponential model, the rising emission can be modelled as the onset of the afterglow, something which is very rarely seen in Swift-X-ray light-curves. We cannot, however, rule out that the hump is a particularly slow early-time flare, or that it is caused by upscattered reverse shock electrons.

  18. GEMINI SPECTROSCOPY OF THE SHORT-HARD GAMMA-RAY BURST GRB 130603B AFTERGLOW AND HOST GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Cucchiara, A.; Prochaska, J. X.; Werk, J. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Perley, D.; Cao, Y. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd, Pasadena, CA 91125 (United States); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD (United States); Cardwell, A.; Turner, J. [Gemini South Observatory, AURA, Casilla 603, La Serena (Chile); Bloom, J. S. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Cobb, B. E., E-mail: acucchia@ucolick.org [The George Washington University, Washington, DC (United States)

    2013-11-10

    We present early optical photometry and spectroscopy of the afterglow and host galaxy of the bright short-duration gamma-ray burst GRB 130603B discovered by the Swift satellite. Using our Target of Opportunity program on the Gemini South telescope, our prompt optical spectra reveal a strong trace from the afterglow superimposed on continuum and emission lines from the z = 0.3568 ± 0.0005 host galaxy. The combination of a relatively bright optical afterglow (r' = 21.52 at Δt = 8.4 hr), together with an observed offset of 0.''9 from the host nucleus (4.8 kpc projected distance at z = 0.3568), allow us to extract a relatively clean spectrum dominated by afterglow light. Furthermore, the spatially resolved spectrum allows us to constrain the properties of the explosion site directly, and compare these with the host galaxy nucleus, as well as other short-duration GRB host galaxies. We find that while the host is a relatively luminous (L∼0.8 L{sup *}{sub B}), star-forming (SFR = 1.84 M{sub ☉} yr{sup –1}) galaxy with almost solar metallicity, the spectrum of the afterglow exhibits weak Ca II absorption features but negligible emission features. The explosion site therefore lacks evidence of recent star formation, consistent with the relatively long delay time distribution expected in a compact binary merger scenario. The star formation rate (SFR; both in an absolute sense and normalized to the luminosity) and metallicity of the host are both consistent with the known sample of short-duration GRB hosts and with recent results which suggest GRB 130603B emission to be the product of the decay of radioactive species produced during the merging process of a neutron-star-neutron-star binary ({sup k}ilonova{sup )}. Ultimately, the discovery of more events similar to GRB 130603B and their rapid follow-up from 8 m class telescopes will open new opportunities for our understanding of the final stages of compact-objects binary systems and provide crucial

  19. Nitric oxide kinetics in the afterglow of a diffuse plasma filament

    Science.gov (United States)

    Burnette, D.; Montello, A.; Adamovich, I. V.; Lempert, W. R.

    2014-08-01

    A suite of laser diagnostics is used to study kinetics of vibrational energy transfer and plasma chemical reactions in a nanosecond pulse, diffuse filament electric discharge and afterglow in N2 and dry air at 100 Torr. Laser-induced fluorescence of NO and two-photon absorption laser-induced fluorescence of O and N atoms are used to measure absolute, time-resolved number densities of these species after the discharge pulse, and picosecond coherent anti-Stokes Raman spectroscopy is used to measure time-resolved rotational temperature and ground electronic state N2(v = 0-4) vibrational level populations. The plasma filament diameter, determined from plasma emission and NO planar laser-induced fluorescence images, remains nearly constant after the discharge pulse, over a few hundred microseconds, and does not exhibit expansion on microsecond time scale. Peak temperature in the discharge and the afterglow is low, T ≈ 370 K, in spite of significant vibrational nonequilibrium, with peak N2 vibrational temperature of Tv ≈ 2000 K. Significant vibrational temperature rise in the afterglow is likely caused by the downward N2-N2 vibration-vibration (V-V) energy transfer. Simple kinetic modeling of time-resolved N, O, and NO number densities in the afterglow, on the time scale longer compared to relaxation and quenching time of excited species generated in the plasma, is in good agreement with the data. In nitrogen, the N atom density after the discharge pulse is controlled by three-body recombination and radial diffusion. In air, N, NO and O concentrations are dominated by the reverse Zel'dovich reaction, N + NO → N2 + O, and ozone formation reaction, O + O2 + M → O3 + M, respectively. The effect of vibrationally excited nitrogen molecules and excited N atoms on NO formation kinetics is estimated to be negligible. The results suggest that NO formation in the nanosecond pulse discharge is dominated by reactions of excited electronic states of nitrogen, occurring on

  20. Scintillation, Afterglow and Thermoluminescence of CsI:Tl,Sm

    Science.gov (United States)

    Kappers, L. A.; Bartram, R. H.; Hamilton, D. S.; Lempicki, A.; Brecher, C.; Gaysinskiy, V.; Ovechkina, E. E.; Nagarkar, V. V.

    2010-11-01

    Experiments on co-doped CsI:Tl,Sm suggest that samarium electron traps scavenge electrons from thallium traps and that electrons subsequently released by samarium recombine non-radiatively with trapped holes, thus suppressing afterglow. These experiments support the inference that electrons tunnel freely between samarium ions and are trapped preferentially as substitutional Sm+ near VKA(Tl+) centers where non-radiative recombination is the rate-limiting step. Combined radioluminescence, afterglow and thermoluminescence on single-crystal samples of CsI:Tl and CsI:Tl,Sm, recorded sequentially at adjusted gain settings following low-temperature irradiation, reveal reversible radiation damage as well.

  1. FTIR Analysis of Flowing Afterglow from a High-Frequency Spark Discharge

    Science.gov (United States)

    White, Allen; Hieftje, Gary M.; Ray, Steve; Pfeuffer, Kevin

    2014-06-01

    Plasmas are often used as ionization sources for ambient mass spectrometry (AMS). Here, the flowing afterglow of a novel high-energy spark discharge system, operated in nitrogen at high repetition rates, is investigated as a source for AMS. The spark discharge here is the same as that of an automobile ignition circuit.Combustion in automobile engines is initiated by a spark ignition system that is designed to deliver short-duration,high-voltage sparks to multiple engine cylinders. The arrangement utilized in this study is a modified discharge configuration designed to produce similarly short-duration, high-voltage discharges. It consists of an automotive ignition coil that is activated by a spark initiation circuit that discharges in turn into a cell with neutral gas input flow and ultimately into the collection orifice of a mass spectrometer. The discharge voltage is approximately 40kV at 800 Hz. High-frequency spark discharges in a nitrogen flow produce reagent ions such as NO+. In order to better evaluate the effectiveness of the discharge in producing reagent ions, an FTIR is utilized to measure IR active species such as nitric oxide, hydroxide, ozone, and water in the afterglow of the spark discharge during variation of discharge parameters. Time-resolved IR emission spectra provide additional insight into the reagent ion production mechanisms.

  2. GRB 090426: Discovery of a jet break in a short burst afterglow

    CERN Document Server

    Guelbenzu, A Nicuesa; Rossi, A; Kann, D A; Krühler, T; Greiner, J; Rau, A; E., F Olivares; Afonso, P M J; Filgas, R; Yoldaş, A Küpcü; McBreen, S; Nardini, M; Schady, P; Schmidl, S; Updike, A C; Yoldaş, A

    2011-01-01

    Context: The link between the duration of GRBs and the nature of their progenitors remains disputed. Short bursts (with durations of less than ~2 s) are less frequently observed, technically more difficult to localize, and exhibit significantly fainter afterglows. Aims: It is of critical importance to establish whether the burst duration can reliably distinguish the different GRB population models of collapsars and compact stellar mergers. The Swift GRB 090426 provides an unique opportunity to address this question. Its duration (T_90=1.28 s) places GRB 090426 firmly in the short burst population, while the high redshift (z=2.609), host galaxy properties, and prompt emission spectral characteristics are more similar to those of long-duration GRBs. Methods: On the basis of data obtained with the Tautenburg 2m telescope (Germany) and the 7-channel imager GROND (La Silla, Chile), we compiled the most finely sampled light curve available for a short burst optical/NIR afterglow. The light curve was then analysed i...

  3. Study of GRB light curve decay indices in the afterglow phase

    CERN Document Server

    Del Vecchio, Roberta; Ostrowski, Michał

    2016-01-01

    In this work we study the distribution of temporal power-law decay indices, $\\alpha$, in the Gamma Ray Burst (GRB) afterglow phase, fitted for $176$ GRBs (139 long GRBs, 12 short GRBs {\\it with extended emission} and 25 X-Ray Flashes (XRFs)) with known redshifts. These indices are compared to the values of characteristic afterglow luminosity, $L_a$, the time, $T_a^*$, and the decay index, $\\alpha_W$, derived with global light curve fitting using the \\cite{willingale07} model. This model fitting yields similar distributions of $\\alpha_W$ to the fitted $\\alpha$, but for individual bursts a difference can be significant. Analysis of the ($\\alpha$, $L_a$) distribution reveals only a weak correlation of these quantities. However, we discovered a significant regular trend when studying GRB $\\alpha$ values along the $L_a$ versus $T_a^*$ (LT) distribution, with systematic variation of $\\alpha$ parameter distribution with luminosity for any selected $T_a^*$. We analyze this systematics with respect to the fitted LT co...

  4. The radio afterglow of Swift J1644+57 reveals a powerful jet with fast core and slow sheath

    Science.gov (United States)

    Mimica, P.; Giannios, D.; Metzger, B. D.; Aloy, M. A.

    2015-07-01

    We model the non-thermal transient Swift J1644+57 as resulting from a relativistic jet powered by the accretion of a tidally disrupted star on to a supermassive black hole. Accompanying synchrotron radio emission is produced by the shock interaction between the jet and the dense circumnuclear medium, similar to a gamma-ray burst afterglow. An open mystery, however, is the origin of the late-time radio re-brightening, which occurred well after the peak of the jetted X-ray emission. Here, we systematically explore several proposed explanations for this behaviour by means of multidimensional hydrodynamic simulations coupled to a self-consistent radiative transfer calculation of the synchrotron emission. Our main conclusion is that the radio afterglow of Swift J1644+57 is not naturally explained by a jet with a one-dimensional top-hat angular structure. However, a more complex angular structure comprised of an ultrarelativistic core (Lorentz factor Γ ˜ 10) surrounded by a slower (Γ ˜ 2) sheath provides a reasonable fit to the data. Such a geometry could result from the radial structure of the super-Eddington accretion flow or as the result of jet precession. The total kinetic energy of the ejecta that we infer of ˜ few 1053 erg requires a highly efficient jet launching mechanism. Our jet model providing the best fit to the light curve of the on-axis event Swift J1644+57 is used to predict the radio light curves for off-axis viewing angles. Implications for the presence of relativistic jets from tidal disruption events (TDEs) detected via their thermal disc emission, as well as the prospects for detecting orphan TDE afterglows with upcoming wide-field radio surveys and resolving the jet structure with long baseline interferometry, are discussed.

  5. Anatomy of A Dark Burst - The Afterglow of GRB 060108

    CERN Document Server

    Oates, S R; Piranomonte, S; Page, K L; De Pasquale, M; Monfardini, A; Melandri, A; Zane, S; Guidorzi, C; Malesani, D; Gomboc, A; Bannister, N; Blustin, A J; Capalbi, M; Carter, D; D'Avanzo, P; Kobayashi, S; Krimm, H A; O'Brien, P T; Page, M J; Smith, R J; Steele, I A; Tanvir, N

    2006-01-01

    We report the first detection of an optical afterglow of a GRB (060108) that would have been classified as 'dark' in the absence of deep, rapid ground-based optical imaging with the 2-m robotic Faulkes Telesscope (FTN). Our multiwavelength analysis reveals an X-ray light curve typical of many Swift long GRBs (3-segments plus flare). Its optical afterglow, however, was already fainter than the detection limit of the UVOT within 100s of the burst. Optical imaging in BVRi' filters with the FTN began 2.75 minutes after the burst and resulted in the detection of the optical afterglow at 5.3 minutes, with a UKIRT K-band identification at ~45 mins. R and i'-band light curves are consistent with a single power law decay in flux, F(t) prop t^-a where a=0.43+/-0.08, or a 2-segment light curve with a steep decay a_1 <0.88, flattening to a_2 ~ 0.31, with evidence for rebrightening at i' band. Deep VLT R-band imaging at ~12 days reveals a faint, extended object (R ~23.5 mag) at the location of the afterglow. Although t...

  6. The Orsay polarized electron source from a flowing helium afterglow

    Science.gov (United States)

    Arianer, J.; Brissaud, I.; Essabaa, S.; Humblot, H.; Zerhouni, W.

    1993-12-01

    A polarized electron source was designed at Orsay. We have chosen to adapt the flowing helium afterglow source working at Rice University because it provides a very high polarization. We have investigated a new way for the optical pumping of the helium metastables. An 85% electron polarization was reached.

  7. Metastable atomic species in the N{sub 2} flowing afterglow

    Energy Technology Data Exchange (ETDEWEB)

    Levaton, J. [Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol - CTBE/CNPEM, Caixa Postal 6170, 13083-970 Campinas, Sao Paulo (Brazil); Amorim, J., E-mail: jayr.amorim@bioetanol.org.br [Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol - CTBE/CNPEM, Caixa Postal 6170, 13083-970 Campinas, Sao Paulo (Brazil)

    2012-03-13

    Graphical abstract: Calculated N({sup 4}S), N({sup 2}D) and N({sup 2}P) absolute densities as a function of the afterglow time. Highlights: Black-Right-Pointing-Pointer Nitrogen flowing post-discharge. Black-Right-Pointing-Pointer N({sup 4}S) and N({sup 2}D) densities. Black-Right-Pointing-Pointer Kinetic numerical model of the nitrogen afterglow. - Abstract: We have studied by optical emission spectroscopy the post-discharge of a pure N{sub 2} DC flowing discharge in such experimental conditions that the pink afterglow and the Lewis-Rayleigh afterglow occur. The emission profiles originated from the N{sub 2}(B{sup 3}{Pi}{sub g}), N{sub 2}(C{sup 3}{Pi}{sub u}) and N{sub 2}{sup +}(B{sup 2}{Sigma}{sub u}{sup +}) states and the N{sub 2}(B{sup 3}{Pi}{sub g},6{<=}v{<=}12) and N{sub 2}(C{sup 3}{Pi}{sub u},0{<=}v{<=}4) vibrational distributions were obtained in the post-discharge region. With basis on the works of Bockel et al. [S. Bockel, A.M. Diamy, A. Ricard, Surf. Coat. Tech. 74 (1995) 474] and Amorim and Kiohara [J. Amorim, V. Kiohara, Chem. Phys. Lett. 385 (2004) 268], we have obtained the experimental N({sup 4}S) and N({sup 2}D) relative densities along the post-discharge. A numerical model, previously developed to describe the neutral atomic, molecular and ionic species in the afterglow, was improved to include the kinetics of N({sup 2}D) and N({sup 2}P) states. Several kinetic mechanisms leading to the production of N({sup 2}D) in the post-discharge have been studied in order to explain the experimental data. We have determined that the dominant one is the reaction N{sub 2}(X{sup 1}{Sigma}{sub g}{sup +},v>8)+N({sup 4}S){yields}N{sub 2}(X{sup 1}{Sigma}{sub g}{sup +})+N({sup 2}D) with an estimated rate constant of 7 Multiplication-Sign 10{sup -14} cm{sup 3} s{sup -1}. Also, the fit of the numerical density profiles of N{sub 2}(C{sup 3}{Pi}{sub u}) and N{sub 2}{sup +}(B{sup 2}{Sigma}{sub u}{sup +}) to the experimental ones has provided the rate constant for reaction

  8. Modeling the Multi-Band Afterglow of GRB 130831A: Evidence for a Spinning-Down Magnetar Dominated by Gravitational Wave Losses?

    CERN Document Server

    Zhang, Q; Zong, H S

    2016-01-01

    The X-ray afterglow of GRB 130831A shows an "internal plateau" with a decay slope of $\\sim$ 0.8, followed by a steep drop at around $10^5$ s with a slope of $\\sim$ 6. After the drop, the X-ray afterglow continues with a much shallower decay. The optical afterglow exhibits two segments of plateaus separated by a luminous optical flare, followed by a normal decay with a slope basically consistent with that of the late-time X-ray afterglow. The decay of the internal X-ray plateau is much steeper than what we expect in the simplest magnetar model. We propose a scenario in which the magnetar undergoes gravitational-wave-driven r-mode instability, and the spin-down is dominated by gravitational wave losses up to the end of the steep plateau, so that such a relatively steep plateau can be interpreted as the internal emission of the magnetar wind and the sharp drop can be produced when the magnetar collapses into a black hole. This scenario also predicts an initial X-ray plateau lasting for hundreds of seconds with a...

  9. Synthesis of Long Afterglow Photoluminescent Materials Sr2MgSi2O7∶Eu2+, Dy3+ by Sol-Gel Method

    Institute of Scientific and Technical Information of China (English)

    Geng Xiujuan; Chen Yongjie; Qiu Guanming; Xiao Linjiu; Yan Changhao; Sun Yanbin

    2005-01-01

    Long afterglow photoluminescent materials Sr2MgSi2O7 doped with Eu2+, Dy3+ were prepared by sol-gel method. The synthesized samples were characterized by X-ray diffraction. The excitation spectrum, emission spectrum and long decay curve were measured and analyzed. XRD pattern indicates that phosphor is with Sr2MgSi2O7 crystal structure. The wide range of excitation wavelength indicates that luminescent material can be excited by light from ultraviolet ray to visible light. The main peak of emission spectrum is located at 466 nm. Sample excited by visible light can emit bright blue light, and the afterglow time lasts more than 8 h.

  10. Late Time Observations of the Afterglow and Environment of GRB 030329

    CERN Document Server

    Taylor, G B; Pihlström, Y M; Ghosh, T; Salter, C

    2004-01-01

    We present Very Long Baseline Interferometry (VLBI) observations 217 days after the gamma-ray burst of 2003 March 29. These observations provide further measurements of the size and position of GRB 030329 that are used to constrain the expansion rate and proper motion of this nearby GRB. The expansion rate appears to be slowing down with time, favoring expansion into a constant density interstellar medium, rather than a circumstellar wind with an r^-2 density profile. We also present late time Arecibo observations of the redshifted HI and OH absorption spectra towards GRB 030329. No absorption (or emission) is seen allowing us to place limits on the atomic neutral hydrogen of N_H < 8.5 x 10^20 cm^-2, and molecular hydrogen of N_H_2 < 1.4 x 10^22 cm^-2. Finally, we present VLA limits on the radio polarization from the afterglow of <2% at late times.

  11. Gamma-ray bursts optical afterglows in the deep Newtonian phase

    CERN Document Server

    Huang, Y F

    2003-01-01

    Gamma-ray burst remnants become trans-relativistic typically in days to tens of days, and they enter the deep Newtonian phase in tens of days to months, during which the majority of shock-accelerated electrons will no longer be highly relativistic. However, a small portion of electrons are still accelerated to ultra-relativistic speeds and capable of emitting synchrotron radiation. The distribution function for electrons is re-derived here so that synchrotron emission from these relativistic electrons can be calculated. Based on the revised model, optical afterglows from both isotropic fireballs and highly collimated jets are studied numerically, and compared to analytical results. In the beamed cases, it is found that, in addition to the steepening due to the edge effect and the lateral expansion effect, the light curves are universally characterized by a flattening during the deep Newtonian phase.

  12. Early afterglow, magnetized central engine, and a quasi-universal jet configuration for long GRBs

    CERN Document Server

    Zhang, B; Kobayashi, S; Lloyd-Ronning, N M; Mészáros, P; Dai, Xinyu; Kobayashi, Shiho; Lloyd-Ronning, Nicole M.; Meszaros, Peter; Zhang, Bing

    2003-01-01

    Two separate topics are discussed. (1) We describe the classifications of the long GRB early afterglow lightcurves within the framework of the fireball shock model, focusing on the interplay between the reverse and forward shock emission components. We will also provide evidence that the central engine of at least two bursts are entrained with strong magnetic fields, and discuss the implications of this result for our understanding of the GRB phenomenon; (2) We argue that the current gamma-ray burst (GRB) and X-ray flash (XRF) data are consistent with a picture that all GRB-XRF jets are structured and quasi-universal, with a typical Gaussian-like jet structure.

  13. Plasma instability in the afterglow of electron cyclotron resonance discharge sustained in a mirror trap

    Energy Technology Data Exchange (ETDEWEB)

    Izotov, I.; Mansfeld, D.; Skalyga, V.; Zorin, V. [Institute of Applied Physics, RAS, 46 Ulyanova St., 603950 Nizhny Novgorod (Russian Federation); Grahn, T.; Kalvas, T.; Koivisto, H.; Komppula, J.; Peura, P.; Tarvainen, O.; Toivanen, V. [Department of Physics, University of Jyvaeskylae, P.O. Box 35 (YFL), 40500 Jyvaeskylae (Finland)

    2012-12-15

    The work presented in this article is devoted to time-resolved diagnostics of non-linear effects observed during the afterglow plasma decay of a 14 GHz electron cyclotron resonance ion source operated in pulsed mode. Plasma instabilities that cause perturbations of the extracted ion current during the decay were observed and studied. It is shown that these perturbations are associated with precipitation of high energy electrons along the magnetic field lines and strong bursts of bremsstrahlung emission. The effect of ion source settings on the onset of the observed instabilities was investigated. Based on the experimental data and estimated plasma properties, it is assumed that the instabilities are of cyclotron type. The conclusion is supported by a comparison to other types of plasma devices which exhibit similar characteristics but which operate in a different plasma confinement regime.

  14. The radio afterglow of Swift J1644+57 reveals a powerful jet with fast core and slow sheath

    CERN Document Server

    Mimica, P; Metzger, B D; Aloy, M A

    2015-01-01

    We model the non-thermal transient Swift J1644+57 as resulting from a relativistic jet powered by the accretion of a tidally-disrupted star onto a super-massive black hole. Accompanying synchrotron radio emission is produced by the shock interaction between the jet and the dense circumnuclear medium, similar to a gamma-ray burst afterglow. An open mystery, however, is the origin of the late-time radio rebrightening, which occurred well after the peak of the jetted X-ray emission. Here, we systematically explore several proposed explanations for this behavior by means of multi-dimensional hydrodynamic simulations coupled to a self-consistent radiative transfer calculation of the synchrotron emission. Our main conclusion is that the radio afterglow of Swift J1644+57 is not naturally explained by a jet with a one-dimensional top-hat angular structure. However, a more complex angular structure comprised of an ultra-relativistic core (Lorentz factor $\\Gamma \\sim 10$) surrounded by a slower ($\\Gamma \\sim $ 2) sheat...

  15. Modeling and assessment of long afterglow decay curves.

    Science.gov (United States)

    Tsai, Chi-Yang; Lin, Jeng-Wen; Huang, Yih-Ping; Huang, Yung-Chieh

    2014-01-01

    Multiple exponential equations have been successfully fitted to experimental long afterglow decay curve data for some phosphor materials by previous researchers. The calculated decay constants in such equations are used to assess the phosphorescence characteristics of an object. This study generates decay constants from experimental test data and from existing literature for comparison. It shows that the decay constants of an object may not be invariant and that they are dependent on phosphor material, temperature, irradiation intensity, sample thickness, and phosphor density for samples. In addition, the use of different numbers of exponential components in interpretation leads to different numerical results for decay constants. The relationship between the calculated decay constants and the afterglow characteristics of an object is studied and discussed in this paper. The appearance of the luminescence intensity is less correlated to the decay constants than to the time-invariant constants in an equation.

  16. Modeling and Assessment of Long Afterglow Decay Curves

    Directory of Open Access Journals (Sweden)

    Chi-Yang Tsai

    2014-01-01

    Full Text Available Multiple exponential equations have been successfully fitted to experimental long afterglow decay curve data for some phosphor materials by previous researchers. The calculated decay constants in such equations are used to assess the phosphorescence characteristics of an object. This study generates decay constants from experimental test data and from existing literature for comparison. It shows that the decay constants of an object may not be invariant and that they are dependent on phosphor material, temperature, irradiation intensity, sample thickness, and phosphor density for samples. In addition, the use of different numbers of exponential components in interpretation leads to different numerical results for decay constants. The relationship between the calculated decay constants and the afterglow characteristics of an object is studied and discussed in this paper. The appearance of the luminescence intensity is less correlated to the decay constants than to the time-invariant constants in an equation.

  17. Scintillation, Afterglow and Thermoluminescence of CsI:Tl,Sm

    Energy Technology Data Exchange (ETDEWEB)

    Kappers, L A; Bartram, R H; Hamilton, D S; Lempicki, A; Brecher, C; Gaysinskiy, V; Ovechkina, E E; Nagarkar, V V, E-mail: lawrence.kappers@uconn.edu

    2010-11-15

    Experiments on co-doped CsI:Tl,Sm suggest that samarium electron traps scavenge electrons from thallium traps and that electrons subsequently released by samarium recombine non-radiatively with trapped holes, thus suppressing afterglow. These experiments support the inference that electrons tunnel freely between samarium ions and are trapped preferentially as substitutional Sm{sup +} near V{sub KA}(Tl{sup +}) centers where non-radiative recombination is the rate-limiting step. Combined radioluminescence, afterglow and thermoluminescence on single-crystal samples of CsI:Tl and CsI:Tl,Sm, recorded sequentially at adjusted gain settings following low-temperature irradiation, reveal reversible radiation damage as well.

  18. Estimation of the detectability of optical orphan afterglows

    CERN Document Server

    Zou, Y C; Dai, Z G

    2006-01-01

    Considering two main assumptions: no sideways expansion and the distribution of half-opening angle of jetted ejecta of gamma-ray bursts, we estimate the detectability of optical orphan afterglows. We show that the former assumption leads to more orphans to be detected while the latter greatly depresses the detectability compared with one single opening angle $\\theta_j=0.1$ model. We also consider the influence of other parameters, and find that the effects of ejecta energy $E_j$, post-jet-break temporal index $-\\alpha_2$ and the distribution of half-opening angle of the jet are important while the index of electron energy distribution $p$, electron energy equipartition factor $\\epsilon_e$ and environment density $n$ are insignificant. If the $E_j$ and $\\alpha_2$ are determined by other methods, one can constrain the distribution of half-opening angle of jets by observation of orphan afterglows.

  19. Multi-wavelength afterglow observations of the high redshift GRB 050730

    OpenAIRE

    2006-01-01

    GRB 050730 is a long duration high-redshift burst (z=3.967) discovered by Swift. The afterglow shows variability and is well monitored over a wide wavelength range. We present comprehensive temporal and spectral analysis of the afterglow of GRB 050730 including observations from the millimeter to X-rays. We use multi-wavelength afterglow data to understand the temporal and spectral decay properties with superimposed variability of this high redshift burst. Five telescopes were used to study t...

  20. Spectroscopic Observations of the Bright Afterglow of GRB021004

    Science.gov (United States)

    Harrison, Fiona

    2001-09-01

    One of the holy grails of gamma-ray burst research is to detect X-ray line signatures from an afterglow with high statistical significance. Of all possible observations, this perhaps offers the best chance of constraining the GRB mechanism and environment, and could provide the "smoking gun" signature connecting GRBs to massive stellar deaths. In order to accomplish this, we know long observations within one day of the event are necessary.

  1. The low-extinction afterglow in the solar-metallicity host galaxy of gamma-ray burst 110918A

    CERN Document Server

    Elliott, J; Greiner, J; Savaglio, S; E., F Olivares; Rau, A; Postigo, A de Ugarte; Sánchez-Ramírez, R; Wiersema, K; Schady, P; Kann, D A; Filgas, R; Nardini, M; Berger, E; Fox, D; Gorosabel, J; Klose, S; Levan, A; Guelbenzu, A Nicuesa; Rossi, A; Schmidl, S; Sudilovsky, V; Tanvir, N R; Thöne, C C

    2013-01-01

    Metallicity is theoretically thought to be a fundamental driver in gamma-ray burst (GRB) explosions and energetics, but is still, even after more than a decade of extensive studies, not fully understood. This is largely related to two phenomena: a dust-extinction bias, that prevented high-mass and thus likely high-metallicity GRB hosts to be detected in the first place, and a lack of efficient instrumentation, that limited spectroscopic studies including metallicity measurements to the low-redshift end of the GRB host population. The subject of this work is the very energetic GRB 110918A, for which we measure a redshift of z=0.984. GRB 110918A gave rise to a luminous afterglow with an intrinsic spectral slope of b=0.70, which probed a sight-line with little extinction (A_V=0.16 mag) typical of the established distributions of afterglow properties. Photometric and spectroscopic follow-up observations of the galaxy hosting GRB 110918A, including optical/NIR photometry with GROND and spectroscopy with VLT/X-shoo...

  2. Early re-brightening of the afterglow of GRB 050525a

    CERN Document Server

    Klotz, A; Atteia, J L; Stratta, G; Behrend, R; Malacrino, F; Damerdji, Y

    2005-01-01

    We present time resolved optical data acquired by the TAROT automated observatory on the afterglow of GRB 050525a from 6 to 136 minutes after the GRB. We evidence a rapid re-brightening of 0.65 magnitude of the afterglow at $\\sim$ 33 min after the GRB. The decay slope $\\alpha$ is $1.14\\pm 0.07$ in the first part and is $1.23\\pm 0.27$ after the re-brightening event. The afterglow of GRB 050525a is the third known afterglow that exhibits a re-brightening event begining at 0.01--0.02 day in the rest time frame.

  3. Steepening of Afterglow Decay for Jets Interacting with Stratified Media

    CERN Document Server

    Kumar, P; Kumar, Pawan; Panaitescu, Alin

    2000-01-01

    We calculate light-curves for Gamma-Ray Burst afterglows when material ejected in the explosion is confined to a jet which propagates in a medium with a power-law density profile. The observed light-curve decay steepens by a factor of $\\Gamma^2$ when an observer sees the edge of the jet. In a uniform density medium the increase in the power-law index ($\\beta$) of the light-curve as a result of this {\\it edge effect} is $\\sim0.7$ and is completed over one decade in observer time. For a pre-ejected stellar wind ($\\rho \\propto r^{-2}$) $\\beta$ increases by $\\sim0.4$ over two decades in time due to the edge effect and the steepening of the light-curve due to the jet sideways expansion takes about four decades in time. Therefore, a break in the light-curve for a jet in a wind model is unlikely to be detected even for very narrow jets of opening angle of a few degrees or less, in which case the lateral expansion occurs at early times when the afterglow is bright. The light-curve for the afterglow of GRB 990510, for...

  4. Rates, Flux Densities, and Spectral Indices of Meteor Radio Afterglows

    CERN Document Server

    Obenberger, K S; Hancock, P J; Holmes, J M; Pedersen, T R; Schinzel, F K; Taylor, G B

    2016-01-01

    Using the narrowband all-sky imager mode of the LWA1 we have now detected 30 transients at 25.6 MHz, 1 at 34 MHz, and 93 at 38.0 MHz. While we have only optically confirmed that 37 of these events are radio afterglows from meteors, evidence suggests that most, if not all, are. Using the beam-forming mode of the LWA1 we have also captured the broadband spectra between 22.0 and 55.0 MHz of four events. We compare the smooth, spectral components of these four events and fit the frequency dependent flux density to a power law, and find that the spectral index is time variable, with the spectrum steepening over time for each meteor afterglow. Using these spectral indices along with the narrow band flux density measurements of the 123 events at 25.6 and 38 MHz, we predict the expected flux densities and rates for meteor afterglows potentially observable by other low frequency radio telescopes.

  5. Intrinsic spatial resolution limitations due to differences between positron emission position and annihilation detection localization; Limitacoes da resolucao espacial intrinseca devido as diferencas entre a posicao da emissao do positron e a deteccao da localizacao de aniquilacao

    Energy Technology Data Exchange (ETDEWEB)

    Perez, Pedro; Malano, Francisco; Valente, Mauro, E-mail: valente@famaf.unc.edu.ar [Universidad Nacional de Cordoba, Cordoba (Argentina). Fac. de Matematica, Astronomia y Fisica (FaMAF)

    2012-07-01

    Since its successful implementation for clinical diagnostic, positron emission tomography (PET) represents the most promising medical imaging technique. The recent major growth of PET imaging is mainly due to its ability to trace the biologic pathways of different compounds in the patient's body, assuming the patient can be labeled with some PET isotope. Regardless of the type of isotope, the PET imaging method is based on the detection of two 511-keV gamma photons being emitted in opposite directions, with almost 180 deg between them, as a consequence of electron-positron annihilation. Therefore, this imaging method is intrinsically limited by random uncertainties in spatial resolutions, related with differences between the actual position of positron emission and the location of the detected annihilation. This study presents an approach with the Monte Carlo method to analyze the influence of this effect on different isotopes of potential implementation in PET. (author)

  6. Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} intrinsic Josephson junction stacks with improved cooling: Coherent emission above 1 THz

    Energy Technology Data Exchange (ETDEWEB)

    Ji, M.; An, D. Y.; Li, M. Y.; Zhou, X. J.; Wang, H. B., E-mail: hbwang1000@gmail.com [Research Institute of Superconductor Electronics, Nanjing University, Nanjing 210093 (China); National Institute for Materials Science, Tsukuba 3050047 (Japan); Yuan, J.; Hatano, T. [National Institute for Materials Science, Tsukuba 3050047 (Japan); Gross, B.; Rudau, F.; Koelle, D.; Kleiner, R. [Physikalisches Institut and Center for Collective Quantum Phenomena in LISA+, Universität Tübingen, D-72076 Tübingen (Germany); Huang, Y.; Sun, H. C.; Zhu, Q.; Li, J.; Xu, W. W.; Jin, B. B.; Wu, P. H. [Research Institute of Superconductor Electronics, Nanjing University, Nanjing 210093 (China); Kinev, N.; Koshelets, V. P. [Kotel' nikov Institute of Radio Engineering and Electronics, 125009 Moscow (Russian Federation)

    2014-09-22

    We report on Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} (BSCCO) intrinsic Josephson junction stacks with improved cooling, allowing for a remarkable increase in emission frequency compared to the previous designs. We started with a BSCCO stack embedded between two gold layers. When mounted in the standard way to a single substrate, the stack emits in the range of 0.43–0.82 THz. We then glued a second, thermally anchored substrate onto the sample surface. The maximum voltage of this better cooled and dimension-unchanged sample was increased and, accordingly, both the emission frequencies and the tunable frequency range were significantly increased up to 1.05 THz and to 0.71 THz, respectively. This double sided cooling may also be useful for other “hot” devices, e.g., quantum cascade lasers.

  7. Effects of Li+ Codoping on the Optical Properties of SrAl2O4 Long Afterglow Ceramic Phosphors

    Directory of Open Access Journals (Sweden)

    Timur Sh. Atabaev

    2014-01-01

    Full Text Available Rare-earths codoped long afterglow strontium aluminate phosphors with high brightness were synthesized via a facile combustion synthesis method using urea as a fuel. The resulted phosphor particles were analyzed by using X-ray diffraction and field emission scanning electron microscope, whereas their optical properties were monitored by photoluminescence spectroscopy. The prepared SrAl2O4:Eu2+, Dy3+, Li+ samples showed a broad green-yellowish emission, peaking at 512 nm when excited by 348 nm. Compared to traditional SrAl2O4:Eu2+, Dy3+ phosphor, the initial luminescence brightness of SrAl2O4:Eu2+, Dy3+, codoped with Li+ improved from 1.89 cd/m2 to 2.71 cd/m2 and the afterglow decay time was prolonged from 103 to 121 min. The possible mechanism of SrAl2O4:Eu2+, Dy3+, Li+ phosphorescence enhancement has been discussed.

  8. A Merger Origin for Short Gamma-Ray Bursts Inferred from the Afterglow and Host Galaxy of GRB 050724

    CERN Document Server

    Berger, E; Cenko, S B; Gal-Yam, A; Soderberg, A M; Kasliwal, M; Leonard, D C; Cameron, P B; Frail, D A; Kulkarni, S R; Murphy, D C; Krzeminski, W; Piran, T; Lee, B L; Roth, K C; Moon, D S; Fox, D B; Harrison, F A; Persson, S E; Schmidt, B P; Penprase, B E; Rich, J; Peterson, B A; Cowie, L L

    2005-01-01

    Despite a rich phenomenology, gamma-ray bursts (GRBs) are divided into two classes based on their duration and spectral hardness -- the long-soft and the short-hard bursts. The discovery of afterglow emission from long GRBs was a watershed event, pinpointing their origin to star forming galaxies, and hence the death of massive stars, and indicating an energy release of about 10^51 erg. While theoretical arguments suggest that short GRBs are produced in the merger of compact object binaries (neutron stars or black holes), the progenitors, energetics, and environments of these events remain elusive despite recent localizations. Here we report the discovery of radio, optical, and infrared afterglow emission from the short-hard GRB 050724, which unambiguously associate it with an elliptical galaxy at a redshift, z=0.257. We show that the energy release is 1-3 orders of magnitude smaller than that of long GRBs, and that the burst ejecta may be collimated in jets. More importantly, the nature of the host galaxy for...

  9. Optical diagnostics and mass spectrometry on the afterglow of an atmospheric pressure Ar/O$_2$ radiofrequency plasma used for polymer surface treatment

    CERN Document Server

    Duluard, Corinne Y; Hubert, Julie; Reniers, François

    2016-01-01

    In the context of polymer surface treatment, the afterglow of an atmospheric pressure Ar/O$_2$ radiofrequency plasma is characterized by optical emission spectroscopy, laser induced fluorescence and mass spectrometry. The influence of the O$_2$ gas flow rate and the source power on the plasma properties (gas temperature, Ar excitation temperature, relative concentrations of O atoms and OH radicals) are evaluated. We show that for plasma torch-to-substrate distances lower than 6 mm, the afterglow creates a protective atmosphere, thus the plasma gas composition interacting with the substrate is well controlled. For higher distances, the influence of ambient air can no longer be neglected and gradients in Ar, O$_2$ and N$_2$ concentrations are measured as a function of axial and vertical position.

  10. Preparation of Non-Grinding Long Afterglow SrAl2O4:Eu2+, Dy3+ Material by Microwave Combustion Method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The non-grinding long afterglow material SrAl2O4:Eu2+, Dy3+ was prepared by combustion method in home microwave oven directly, after dispersant, frother, comburent, and mineralizer were added into the reacting system. XRD analysis showed that the powders were nearly pure SrAl2O4 phase with few other phases, and the size of the grain was 41.1 nm. Fluorescence spectrum results indicated that there were 2 excitation peaks located at 345 and 400 nm, and the emission peak located at 516 nm, afterglow lasted up to 30 min or more. The microwave combustion method has advantages of less time, low temperature and no grinding process, and the material made by the method has good luminescent property.

  11. GRB 081008: from burst to afterglow and the transition phase in between

    CERN Document Server

    Yuan, F; Racusin, J L; Willingale, R; Kruhler, T; O'Brien, P T; Greiner, J; Oates, S R; Rykoff, E S; Aharonian, F; Akerlof, C W; Ashley, M C B; Barthelmy, S D; Filgas, R; Flewelling, H A; Gehrels, N; Gogus, E; Guver, T; Horns, D; Kiziloglu, U; Krimm, H A; McKay, T A; Ozel, M E; Pandey, S B; Phillips, A; Quimby, R M; Rowell, G; Rujopakarn, W; Schaefer, B E; Vestrand, W T; Wheeler, J C; Wren, J; Zheng, W

    2010-01-01

    We present a multi-wavelength study of GRB 081008, at redshift 1.967, by Swift, ROTSE-III and GROND. Compared to other Swift GRBs, GRB 081008 has a typical gamma-ray isotropic equivalent energy output (10^53 erg) during the prompt phase, and displayed two temporally separated clusters of pulses. The early X-ray emission seen by the Swift/XRT was dominated by the softening tail of the prompt emission, producing multiple flares during and after the Swift/BAT detections. Optical observations that started shortly after the first active phase of gamma-ray emission showed two consecutive peaks. We interpret the first optical peak as the onset of the afterglow associated with the early burst activities. A second optical peak, coincident with the later gamma-ray pulses, imposes a small modification to the otherwise smooth lightcurve and thus suggests a minimal contribution from a probable internal component. We suggest the early optical variability may be from continuous energy injection into the forward shock front ...

  12. INTERPRETATION OF THE UNPRECEDENTEDLY LONG-LIVED HIGH-ENERGY EMISSION OF GRB 130427A

    Energy Technology Data Exchange (ETDEWEB)

    Liu Ruoyu; Wang Xiangyu [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wu Xuefeng [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2013-08-20

    High-energy photons (>100 MeV) are detected by the Fermi/Large Area Telescope from GRB 130427A up to almost one day after the burst, with an extra hard spectral component discovered in the high-energy afterglow. We show that this hard spectral component arises from afterglow synchrotron self-Compton (SSC) emission. This scenario can explain the origin of >10 GeV photons detected up to {approx}30, 000 s after the burst, which would be difficult to explain via synchrotron radiation due to the limited maximum synchrotron photon energy. The lower energy multi-wavelength afterglow data can be fitted simultaneously by the afterglow synchrotron emission. The implication of detecting the SSC emission for the circumburst environment is discussed.

  13. Observations of GRB X-ray afterglows with SODART/SRG

    DEFF Research Database (Denmark)

    Brandt, Søren Kristian; Lund, Niels; Pedersen, Henrik

    1998-01-01

    Despite recent progress with the detection of afterglows of Gamma Ray Bursts (GRBs), the nature of these events is unknown. However, important clues to understanding what the GRBs are, may very well be found by studying the X-ray afterglows. The combination on SRG of the MOXE all-sky monitor...

  14. Spectrophotometric analysis of gamma-ray burst afterglow extinction curves with X-Shooter

    NARCIS (Netherlands)

    Japelj, J.; Covino, S.; Gomboc, A.; Vergani, S.D.; Goldoni, P.; Selsing, J.; Cano, Z.; D’Elia, V.; Flores, H.; Fynbo, J.P.U.; Hammer, F.; Hjorth, J.; Jakobsson, P.; Kaper, L.; Kopač, D.; Krühler, T.; Melandri, A.; Piranomonte, S.; Sánchez-Ramírez, R.; Tagliaferri, G.; Tanvir, N.R.; de Ugarte Postigo, A.; Watson, D.; Wijers, R.A.M.J.

    2015-01-01

    We use gamma-ray burst (GRB) afterglow spectra observed with the VLT/X-Shooter spectrograph to measure rest-frame extinction in GRB lines-of-sight by modelling the broadband near-infrared (NIR) to X-ray afterglow spectral energy distributions (SEDs). Our sample consists of nine Swift GRBs, of which

  15. Viewing angle and environment effects in gamma-ray bursts: sources of afterglow diversity

    NARCIS (Netherlands)

    Meszaros, P.; Rees, M.J.; Wijers, R.A.M.J.

    1998-01-01

    We discuss the afterglows from the evolution of both spherical and anisotropic fireballs decelerating in an inhomogeneous external medium. We consider both the radiative and adiabatic evolution regimes and analyze the physical conditions under which these regimes can be used. Afterglows may be expec

  16. The energy budget of GRBs based on updated prompt \\& afterglow observations

    CERN Document Server

    Wygoda, Nahliel; Mandich, Marc-Adrien; Waxman, Eli

    2015-01-01

    We compare the isotropic equivalent 15-2000 keV gamma-ray energy, E_gamma, emitted by a sample of 91 swift Gamma-Ray Bursts (GRBs) with known redshifts, with the isotropic equivalent fireball energy, E_fb, as estimated within the fireball model framework from X-ray afterglow observations of these bursts. The uncertainty in E_gamma, which spans the range of ~10^51 erg to ~10^53.5 erg, is approximately 25% on average, due mainly to the extrapolation from the BAT detector band to the 15-2000 keV band. The uncertainty in E_fb is approximately a factor of 2, due mainly to the X-ray measurements' scatter. We find E_gamma and E_fb to be tightly correlated. The average(std) of {\\eta}^11hr_gamma is approximately log_10(E_gamma/(3{\\epsilon} _eE^11hr_fb)) are -0.34(0.60), and the upper limit on the intrinsic spread of {\\eta}_gamma is approximately 0.5 ({\\epsilon}_e is the fraction of shocked plasma energy carried by electrons and E^x hr_fb is inferred from the X-ray flux at x hours). We also find that E_fb inferred from...

  17. Near-Infrared Emission CuInS/ZnS Quantum Dots: All-in-One Theranostic Nanomedicines with Intrinsic Fluorescence/Photoacoustic Imaging for Tumor Phototherapy.

    Science.gov (United States)

    Lv, Guoxian; Guo, Weisheng; Zhang, Wei; Zhang, Tingbin; Li, Shuyi; Chen, Shizhu; Eltahan, Ahmed Shaker; Wang, Dongliang; Wang, Yuqing; Zhang, Jinchao; Wang, Paul C; Chang, Jin; Liang, Xing-Jie

    2016-09-20

    Many theranostic nanomedicines (NMs) have been fabricated by packaging imaging and therapeutic moieties together. However, concerns about their potential architecture instability and pharmacokinetic complexity remain major obstacles to their clinical translation. Herein, we demonstrated the use of CuInS/ZnS quantum dots (ZCIS QDs) as "all-in-one" theranostic nanomedicines that possess intrinsic imaging and therapeutic capabilities within a well-defined nanostructure. ZCIS QDs were exploited for multispectral optical tomography (MSOT) imaging and synergistic PTT/PDT therapy. Due to the intrinsic fluorescence/MSOT imaging ability of the ZCIS QDs, their size-dependent distribution profiles were successfully visualized at tumor sites in vivo. Our results showed that the smaller nanomedicines (ZCIS NMs-25) have longer tumor retention times, higher tumor uptake, and deeper tumor penetration than the larger nanomedicines (ZCIS NMs-80). The ability of ZCIS QDs to mediate photoinduced tumor ablation was also explored. Our results verified that under a single 660 nm laser irradiation, the ZCIS NMs had simultaneous inherent photothermal and photodynamic effects, resulting in high therapy efficacy against tumors. In summary, the ZCIS QDs as "all-in-one" versatile nanomedicines allow high therapeutic efficacy as well as noninvasively monitoring tumor site localization profiles by imaging techniques and thus hold great potential as precision theranostic nanomedicines.

  18. Optimal Coaddition of Imaging Data for Rapidly Fading Gamma-Ray Burst Afterglows

    CERN Document Server

    Morgan, A N; Roming, P W A; Nousek, J A; Koch, T S; Breeveld, A A; de Pasquale, M; Holland, S T; Kuin, N P M; Page, M J; Still, M

    2008-01-01

    We present a technique for optimal coaddition of image data for rapidly varying sources, with specific application to gamma-ray burst (GRB) afterglows. Unweighted coaddition of rapidly fading afterglow lightcurve data becomes counterproductive relatively quickly. It is better to stop coaddition of the data once noise dominates late exposures. A better alternative is to optimally weight each exposure to maximize the signal-to-noise ratio (S/N) of the final coadded image data. By using information about GRB lightcurves and image noise characteristics, optimal image coaddition increases the probability of afterglow detection and places the most stringent upper limits on non-detections. For a temporal power law flux decay typical of GRB afterglows, optimal coaddition has the greatest potential to improve the S/N of afterglow imaging data (relative to unweighted coaddition), when the decay rate is high, the source count rate is low, and the background rate is high. The optimal coaddition technique is demonstrated ...

  19. Gamma-ray Bursts: Radio Afterglow and Host Galaxy Study with The FAST Telescope

    Science.gov (United States)

    Li, L. B.; Huang, Y. F.; Kong, S. W.; Zhang, Z. B.; Li, D.; Luo, J. J.

    2016-02-01

    For four types of GRBs, namely high-luminosity, low-luminosity, standard and failed GRBs, we calculated their radio afterglow light curves. Meanwhile, considering contributions from host galaxies in radio bands, we statistically investigated the effect of hosts on radio afterglows. It is found that a tight anti-correlation exists between the ratio of radio flux (RRF) of host galaxy to the total radio afterglow peak flux and the observed frequency. Using this method, the host flux densities of those bursts without host measurements can be estimated at low or medium frequencies. We predicted that almost all types of radio afterglows, except that of low-luminosity GRBs, can be observed by FAST up to z = 15 or even more. FAST is expected to significantly expand the samples of GRB radio afterglows and host galaxies.

  20. The Afterglow and Environment of the Short GRB111117A

    CERN Document Server

    Margutti, R; Fong, W; Zauderer, B A; Cenko, S B; Greiner, J; Soderberg, A M; Cucchiara, A; Klose, S; Rossi, A; Schmidl, S; Milisavljevic, D; Sanders, N

    2012-01-01

    We present multi-wavelength observations of the afterglow of the short GRB111117A, and follow-up observations of its host galaxy. From rapid optical and radio observations we place limits of r \\gtrsim 25.5 mag at \\deltat \\approx 0.55 d and F_nu(5.8 GHz) 3-10 degrees (depending on the circumburst density). We conclude that Chandra observations of short GRBs are effective at determining precise positions and robust host galaxy associations in the absence of optical and radio detections.

  1. Pulsed ECR Source in Afterglow Operation at CERN

    CERN Document Server

    Hill, C E

    1995-01-01

    A pulsed 14 GHz ECR4 source, adapted to operate in the afterglow mode, was delivered by GANIL to CERN in the framework of the Heavy Ion Facility Project. After four months of operation to commission the facility, it completed its first operational run of nine weeks at the end of 1994, providing lead ions to nuclear physics and ion cooling experiments. A very stable beam, with a useful length of over 1 ms, of 80 emA of Pb27+ was provided by the source over this period. The operational problems experienced during the commissioning and operation, and the investigations to improve performance for the next experimental physics run are presented.

  2. GRB Afterglows and Other Transients in the SDSS

    OpenAIRE

    Lee, Brian C.; Reichart, Daniel E.

    2003-01-01

    The Sloan Digital Sky Survey (SDSS) will image one quarter of the sky centered on the northern galactic cap and produce a 3-D map of galaxies and quasars found in the sample. An additional 225 deg^2 southern survey will be imaged repeatedly on varying timescales. Here we discuss both archival searches in the SDSS catalog (such as SDSS J24602.54+011318.8) and active searches with the SDSS instruments (such as for GRB 010222) for GRB afterglows and other transient objects.

  3. The bright optical afterglow of the long GRB 001007

    DEFF Research Database (Denmark)

    Ceron, J.M.C.; Castro-Tirado, A.J.; Gorosabel, J.

    2002-01-01

    We present optical follow up observations of the long GRB 001007 between 6.14 hours and similar to468 days after the event. An unusually bright optical afterglow (OA) was seen to decline following a steep power law decay with index alpha = -2.03 +/- 0.11, possibly indicating a break in the light...... curve at t - t(0) ray event provide tentative (1.2σ) evidence for a break in the optical light curve. The spectral index β of the OA yields -1.24 +/- 0.57. These values may be explained both...

  4. GRB 080503 LATE AFTERGLOW RE-BRIGHTENING: SIGNATURE OF A MAGNETAR-POWERED MERGER-NOVA

    Energy Technology Data Exchange (ETDEWEB)

    Gao, He; Ding, Xuan; Wu, Xue-Feng [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Dai, Zi-Gao [School of Astronomy and Space Science, Nanjing University, Nanjing 2100093 (China); Zhang, Bing, E-mail: hug18@psu.edu, E-mail: xfwu@pmo.ac.cn, E-mail: dzg@nju.edu.cn, E-mail: zhang@physics.unlv.edu [Department of Physics and Astronomy, University of Nevada Las Vegas, NV 89154 (United States)

    2015-07-10

    GRB 080503 is a short gamma-ray burst (GRB) detected by Swift and has been classified as a GRB originating from a compact star merger. The soft extended emission and the simultaneous late re-brightening in both the X-ray and optical afterglow light curves raise interesting questions regarding its physical origin. We show that the broadband data of GRB 080503 can be well explained within the framework of the double neutron star merger model, provided that the merger remnant is a rapidly rotating massive neutron star with an extremely high magnetic field (i.e., a millisecond magnetar). We show that the late optical re-brightening is consistent with the emission from a magnetar-powered “merger-nova.” This adds one more case to the growing sample of merger-novae associated with short GRBs. The soft extended emission and the late X-ray excess emission are well connected through a magnetar dipole spin-down luminosity evolution function, suggesting that direct magnetic dissipation is the mechanism to produce these X-rays. The X-ray emission initially leaks from a hole in the merger ejecta pierced by the short GRB jet. The hole subsequently closes after the magnetar spins down and the magnetic pressure drops below ram pressure. The X-ray photons are then trapped behind the merger-nova ejecta until the ejecta becomes optically thin at a later time. This explains the essentially simultaneous re-brightening in both the optical and X-ray light curves. Within this model, future gravitational-wave sources could be associated with a bright X-ray counterpart along with the merger-nova, even if the short GRB jet beams away from Earth.

  5. Ambient magnetic field amplification in shock fronts of relativistic jets: an application to GRB afterglows

    CERN Document Server

    da Silva, G Rocha; Kowal, G; Pino, E M de Gouveia Dal

    2014-01-01

    Strong downstream magnetic fields of order of $\\sim 1$G, with large correlation lengths, are believed to cause the large synchrotron emission at the afterglow phase of gamma ray bursts (GRBs). Despite of the recent theoretical efforts, models have failed to fully explain the amplification of the magnetic field, particularly in a matter dominated scenario. We revisit the problem by considering the synchrotron emission to occur at the expanding shock front of a weakly magnetized relativistic jet over a magnetized surrounding medium. Analytical estimates and a number of high resolution 2D relativistic magneto-hydrodynamical (RMHD) simulations are provided. Jet opening angles of $\\theta = 0^{\\circ} - 20^{\\circ}$, and ambient to jet density ratios of $10^{-4} - 10^2$ were considered. We found that most of the amplification is due to compression of the ambient magnetic field at the contact discontinuity between the reverse and forward shocks at the jet head, with substantial pile-up of the magnetic field lines as t...

  6. Self-organized criticality in X-ray flares of gamma-ray burst afterglows

    CERN Document Server

    Wang, F Y

    2013-01-01

    X-ray flares detected in nearly half of gamma-ray burst (GRB) afterglows are one of the most intriguing phenomena in high-energy astrophysics. All the observations indicate that the central engines of bursts, after the gamma-ray emission has ended, still have long periods of activity, during which energetic explosions eject relativistic materials, leading to late-time X-ray emission. It is thus expected that X-ray flares provide important clues to the nature of the central engines of GRBs, and more importantly, unveil the physical mechanism of the flares themselves, which has so far remained mysterious. Here we report statistical results of X-ray flares of GRBs with known redshifts, and show that X-ray flares and solar flares share three statistical properties: power-law frequency distributions for energies, durations, and waiting times. All of the distributions can be well understood within the physical framework of a self-organized criticality (SOC) system. The statistical properties of X-ray flares of GRBs...

  7. Afterglow characteristics of CaTiO{sub 3}: Pr{sup 3+} prepared by solar furnace

    Energy Technology Data Exchange (ETDEWEB)

    Katayama, Yumiko; Tanabe, Setsuhisa, E-mail: yumiko@h05ktym.mbox.media.kyoto-u.ac.jp [Graduate School of Human and Environmental Studies, Kyoto University, Yoshida-nihonmatsu-cho, Sakyo-ku, Kyoto, 606-8501 (Japan)

    2011-05-15

    We have prepared polycrystalline CaTiO{sub 3}: Pr{sup 3+} showing long-lasting phosphorescence by melting method using a solar furnace. Emission, excitation spectra, phosphorescence decay and thermoluminescence were compared with samples prepared by conventional solid-state reaction in conventional electric furnace (EF) at 1200 deg. C, 5 h in air. The color of the sample prepared by solar furnace (SF-AM) was dark brownish. After heat treatment at 800deg. C, 5h in air atmosphere, a decolorized sample (SF-HT) was obtained. All samples showed Pr{sup 3+}:{sup 1}D{sub 2} {yields} {sup 3}H{sub 4} fluorescence at 613 nm and corresponding afterglow phosphorescence. The SF-AM and SF-HT showed much higher PLE intensity of Pr{sup 3+}:{sup 3}P{sub J} bands in blue region than EF. CaTiO{sub 3}:Pr{sup 3+} made by a solar furnace has a potential to be a red afterglow phosphor even under visible excitation.

  8. An achromatic break in the afterglow of the short GRB 140903A: evidence for a narrow jet

    CERN Document Server

    Troja, E; Cenko, S B; Lien, A; Gehrels, N; Castro-Tirado, A J; Ricci, R; Capone, J; Toy, V; Kutyrev, A; Kawai, N; Cucchiara, A; Fruchter, A; Gorosabel, J; Jeong, S; Levan, A; Perley, D; Sanchez-Ramirez, R; Tanvir, N; Veilleux, S

    2016-01-01

    We report the results of our observing campaign on GRB140903A, a nearby (z=0.351) short duration (T90~0.3 s) gamma-ray burst discovered by Swift. We monitored the X-ray afterglow with Chandra up to 21 days after the burst, and detected a steeper decay of the X-ray flux after approximately 1 day. Continued monitoring at optical and radio wavelengths showed a similar decay in flux at nearly the same time, and we interpret it as evidence of a narrowly collimated jet. By using the standard fireball model to describe the afterglow evolution, we derive a jet opening angle of 5 deg and a collimation-corrected total energy release of 2E50 erg. We further discuss the nature of the GRB progenitor system. Three main lines disfavor a massive star progenitor: the properties of the prompt gamma-ray emission, the age and low star-formation rate of the host galaxy, and the lack of a bright supernova. We conclude that this event was likely originated by a compact binary merger.

  9. Suppression of afterglow in CsI:Tl by codoping with Eu{sup 2+}-I: Experimental

    Energy Technology Data Exchange (ETDEWEB)

    Brecher, C. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States)]. E-mail: cbrecher@rmdinc.com; Lempicki, A. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States); Miller, S.R. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States); Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Glodo, J. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States); Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Ovechkina, E.E. [Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Gaysinskiy, V. [Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Nagarkar, V.V. [Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Bartram, R.H. [Department of Physics, University of Connecticut, Storrs, CT 06269-3046 (United States)

    2006-03-15

    Although CsI:Tl is the brightest and most efficient scintillator material ever developed, its use in fast imaging applications has been hindered by its strong and persistent afterglow. Recent experiments, however, have demonstrated that much of this afterglow can be suppressed by the addition of Eu{sup 2+} to the CsI host lattice. The magnitude of the effect depends strongly on the duration of the pulse of ionizing radiation that excites the scintillation, but is virtually independent of the intensity of that excitation pulse. The codoping also brings about a measurable red shift in the Tl{sup +} emission, suggesting some degree of spatial correlation between the luminophor and the modifying additive. The observations indicate that the Eu{sup 2+} ion exerts its influence not by a quenching process, but rather by introducing a set of electron traps that fundamentally alter the decay kinetics. This is confirmed by the appearance of new glow peaks in the thermoluminescence traces of the codoped material. A consistent mathematical model has been developed to describe the phenomenon, to be discussed in detail in the accompanying paper.

  10. BRIGHT LONG AFTERGLOW PHOSPHORESCENCE GLASS MADE OF SrAl2O4: Eu2+, Dy3+ AND GLASS FRITS

    Institute of Scientific and Technical Information of China (English)

    X.Y. Zhang; Z.F. Cao; L.P. Lu; Z.H. Bai; W.Z. Wang; X.C. Wang

    2005-01-01

    Bright long afterglow phosphorescence glasses were prepared by using SrAl2O4 : Eu2+, Dy3+ phosphors and suitable glass frits together. The SrAl2O4: Eu2+,Dy3+ phosphors were initially prepared by the solid reaction method. Three kinds of glass frits were prepared to match the SrAl2O4: Eu2+,Dy3+ phosphors. Effects of the compositions of the glass frits, the ratios of the phosphors to the frits as well as the firing temperature and firing times on the properties of the samples were discussed. XRD analysis indicated the samples exhibited the typical diffraction peaks of SrAl2O4:Eu2+, Dy3+. The emission spectra of the samples showed broad bands peaking at 510nm. The excitation spectra of the samples showed broad bands ranging from 300 to 480nm. These are believed due to the 5d4f-4f transitions of Eu2+ in the SrAl2O4: Eu2+, Dy3+ phosphors. The afterglow luminescence of the samples excited by a 40W fluorescence lamp for 30min can be observed in the dark for more 10h with the naked eyes. It can find wide applications in many fields.

  11. The Role of Intrinsic and Surface States on the Emission Properties of Colloidal CdSe and CdSe/ZnS Quantum Dots

    Directory of Open Access Journals (Sweden)

    Morello Giovanni

    2007-01-01

    Full Text Available AbstractTime Resolved Photoluminescence (TRPL measurements on the picosecond time scale (temporal resolution of 17 ps on colloidal CdSe and CdSe/ZnS Quantum Dots (QDs were performed. Transient PL spectra reveal three emission peaks with different lifetimes (60 ps, 460 ps and 9–10 ns, from the bluest to the reddest peak. By considering the characteristic decay times and by comparing the energetic separations among the states with those theoretically expected, we attribute the two higher energy peaks to ± 1Uand ± 1L bright states of the fine structure picture of spherical CdSe QDs, and the third one to surface states emission. We show that the contribution of surface emission to the PL results to be different for the two samples studied (67% in the CdSe QDs and 32% in CdSe/ZnS QDs, confirming the decisive role of the ZnS shell in the improvement of the surface passivation.

  12. Gamma-Ray Bursts: Afterglows and Central Engines

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Gamma-ray bursts (GRBs) are the most intense transient gamma-ray events in the sky; this, together with the strong evidence (the isotropic and in homogeneous distribution of GRBs detected by BASTE) that they are located at cosmological distances, makes them the most energetic events ever known. For example, the observed radiation energies of some GRBs are equivalent to the total convertion into radiation of the mass energy of more than one solar mass. This is thousand times stronger than the energy of a supernova explosion. Some unconventional energy mechanism and extremely high conversion efficiency for these mysterious events are required. The discovery of host galaxies and association with supernovae at cosmological distances by the recently launched satellite of BeppoSAX and ground based radio and optical telescopes in GRB afterglow provides further support to the cosmological origin of GRBs and put strong constraints on their central engine. It is the aim of this article to review the possible central engines,energy mechanisms, dynamical and spectral evolution of GRBs, especially focusing on the afterglows in multi-wavebands.

  13. Delayed energy injection model for gamma-ray burst afterglows

    Energy Technology Data Exchange (ETDEWEB)

    Geng, J. J.; Huang, Y. F.; Yu, Y. B. [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Wu, X. F., E-mail: hyf@nju.edu.cn, E-mail: xfwu@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2013-12-10

    The shallow decay phase and flares in the afterglows of gamma-ray bursts (GRBs) are widely believed to be associated with the later activation of the central engine. Some models of energy injection involve a continuous energy flow since the GRB trigger time, such as the magnetic dipole radiation from a magnetar. However, in the scenario involving a black hole accretion system, the energy flow from the fall-back accretion may be delayed for a fall-back time ∼t {sub fb}. Thus, we propose a delayed energy injection model. The delayed energy would cause a notable rise to the Lorentz factor of the external shock, which will 'generate' a bump in the multiple band afterglows. If the delayed time is very short, our model degenerates to the previous models. Our model can explain the significant re-brightening in the optical and infrared light curves of GRB 081029 and GRB 100621A. A considerable fall-back mass is needed to provide the later energy; this indicates that GRBs accompanied with fall-back material may be associated with a low energy supernova so that the fraction of the envelope can survive during eruption. The fall-back time can give meaningful information on the properties of GRB progenitor stars.

  14. The distribution of equivalent widths in long GRB afterglow spectra

    CERN Document Server

    Postigo, A de Ugarte; Thoene, C C; Christensen, L; Gorosabel, J; Milvang-Jensen, B; Schulze, S; Jakobsson, P; Wiersema, K; Sanchez-Ramirez, R; Leloudas, G; Zafar, T; Malesani, D; Hjorth, J

    2012-01-01

    The extreme brightness of gamma-ray burst (GRB) afterglows and their simple spectral shape make them ideal beacons to study the interstellar medium of their host galaxies through absorption line spectroscopy. Using 69 low-resolution GRB afterglow spectra, we conduct a study of the rest-frame equivalent width (EW) distribution of features with an average rest-frame EW larger than 0.5 A. To compare an individual GRB with the sample, we develop EW diagrams as a graphical tool, and we give a catalogue with diagrams for the 69 spectra. We introduce a line strength parameter (LSP) that allows us to quantify the strength of the absorption features as compared to the sample by a single number. Using the distributions of EWs of single-species features, we derive the distribution of column densities by a curve of growth (CoG) fit. We find correlations between the LSP and the extinction of the GRB, the UV brightness of the host galaxies and the neutral hydrogen column density. However, we see no significant evolution of...

  15. Role of the oxidized secondary acceptor QB of photosystem II in the delayed 'afterglow' chlorophyll luminescence.

    Science.gov (United States)

    Ducruet, Jean-Marc; Roman, Miruna; Ortega, Jose Maria; Janda, Tibor

    2005-06-01

    Leaf discs of dark-adapted tobacco plants were excited by 2 flashes and kept in darkness at 20 degrees C for various time periods, then thermoluminescence emission was recorded without freezing the sample. The B band at 30 degrees C decreased with a half-time t1/2 approximately 1 min and the AG band at 45 degrees C with a t1/2 approximately 5 min. This corresponds to the decay kinetics of S2/3 in PS II centres in the state S2/3 QB - (B band) or S2/3 QB. Assuming that the 45 degrees C band is an 'afterglow' emission originating from those centres with an oxidized QB on which an electron is back-transferred from stroma reductants through a pathway induced by warming, the theoretical ratio of the B and AG band was compared to that measured experimentally. After 2 or 3 flashes producing mainly S3, the intensity of AG band encompassed several fold that of the B band, because recombining S3 recreated S2 QB AG-emitting centres. In order to confirm that the AG band is governed by the heat-induced activation of a dark QB-reducing pathway rather than by PS II charge recombination, the AG emission was characterized in triazine-resistant Chenopodium album weed biotypes. In these mutants where the QB pocket is altered, the B band is strongly downshifted to 18 degrees C, compared to 32 degrees C in the wild type, whereas the AG band is only downshifted by 3 or 4 degrees C, demonstrating that S2/3 QB - is not the limiting step of the AG emission.

  16. The flat decay phase in the early X-ray afterglows of Swift GRBs

    CERN Document Server

    Granot, J

    2006-01-01

    Many Swift GRBs show an early phase of shallow decay in their X-ray afterglows, lasting from $t \\sim 10^{2.5} $s to $\\sim 10^4 $s after the GRB, where the flux decays as $\\sim t^{-0.2}-t^{-0.8}$. This is perhaps the most mysterious of the new features discovered by Swift in the early X-ray afterglow, since it is still not clear what causes it. I discuss different possible explanations for this surprising new discovery, as well as their potential implications for the gamma-ray efficiency, the afterglow kinetic energy, and perhaps even for the physics of collisionless relativistic shocks.

  17. Modeling the Radio and Optical/NIR Afterglows of GRB 980703: a Numerical Study

    Science.gov (United States)

    Kong, S. W.; Huang, Y. F.

    2008-10-01

    GRB 980703 has extensive available multiband afterglow data. Especially, its radio afterglows were very bright and monitored until more than 1000 days after the trigger time. This makes GRB 980703 a precious sample in GRB research. We calculate the radio and optical/NIR afterglows of GRB 980703 numerically, by using a set of generic dynamical equations. It is found that the observations consist with the theoretical expectation of the standard fireball model well. Our result suggests that the jet opening angle is ~13°, the number density of the surrounding medium is ~30 cm-3, and the isotropic equivalent kinetic energy of the explosion is ~3.8×1052 ergs.

  18. Radio afterglow of the jetted tidal disruption event Swift J1644+57

    Directory of Open Access Journals (Sweden)

    Mimica P.

    2012-12-01

    Full Text Available The recent transient event Swift J1644+57 has been interpreted as resulting from a relativistic outflow, powered by the accretion of a tidally disrupted star onto a supermassive black hole. This discovery of a new class of relativistic transients opens new windows into the study of tidal disruption events (TDEs and offers a unique probe of the physics of relativistic jet formation and the conditions in the centers of distant quiescent galaxies. Unlike the rapidly-varying γ/X-ray emission from Swift J1644+57, the radio emission varies more slowly and is well modeled as synchrotron radiation from the shock interaction between the jet and the gaseous circumnuclear medium (CNM. Early after the onset of the jet, a reverse shock propagates through and decelerates the ejecta released during the first few days of activity, while at much later times the outflow approaches the self-similar evolution of Blandford and McKee. The point at which the reverse shock entirely crosses the earliest ejecta is clearly observed as an achromatic break in the radio light curve at t ≈ 10 days. The flux and break frequencies of the afterglow constrain the properties of the jet and the CNM, including providing robust evidence for a narrowly collimated jet. I briefly discuss the implications of Swift J1644+57 for the fraction of TDEs accompanied by relativistic jets; the physics of jet formation more broadly; and the prospects for detecting off-axis TDE radio emission, either via follow-up observations of TDE candidates discovered at other wavelengths or blindly with upcoming wide-field radio surveys. The radio rebrightening observed months after the onset of the jet remains a major unsolved mystery, the resolution of which may require considering a jet with more complex (temporal or angular structure.

  19. Dynamics and Afterglow Light Curves of GRB Blast Waves with a Long-lived Reverse Shock

    CERN Document Server

    Uhm, Z Lucas; Hascoet, Romain; Daigne, Frederic; Mochkovitch, Robert; Park, Il H

    2012-01-01

    We perform a detailed study on the dynamics of a relativistic blast wave with the presence of a long-lived reverse shock (RS). Although a short-lived RS has been widely considered, the RS is believed to be long-lived as a consequence of a stratification expected on the ejecta Lorentz factors. The existence of a long-lived RS makes the forward shock (FS) dynamics to deviate from a self-similar Blandford-McKee solution. Employing the "mechanical model" that correctly incorporates the energy conservation for such blast waves with a long-lived RS, we present an accurate solution for both the FS and RS dynamics. We conduct a sophisticated calculation of the afterglow emission. Adopting a Lagrangian description of the blast wave, we keep track of an adiabatic evolution of numerous shells between the FS and RS. An evolution of the electron spectrum is also followed individually for every shell. We then find the FS and RS light curves by integrating over the entire FS and RS shocked regions, respectively. In particul...

  20. Experiments on the Pulsed Afterglow Operation of an ECR Ion Source

    CERN Document Server

    Hill, C

    1999-01-01

    Various experiments have been performed on the 14.5 GHz ECR4 in order to improve the beam yield. The source operates in pulsed "afterglow" mode, and provides currents >120 emA of Pb27+ to the Heavy Ion Facility on an operational basis. In the search for higher beam intensities, the effects of a pulsed biased disk on axis at the injection side were investigated with different pulse timing and voltage settings. Different plasma electrode geometries were also tested, including running the source without a plasma electrode. The use of CF4 as mixing gas was investigated, and high secondary electron emission materials, such as LaB6 and Al2O3, were inserted inside the plasma chamber in an attempt to increase the cold electron density. No proof for higher intensities was seen for any of the tested modifications. On the contrary, several of the modifications resulted in lower source performance, and less stability. Although the source has previously proved to have very stable modes of operation, during the last physic...

  1. The unusual afterglow of GRB 980326 evidence for the $\\gamma$-ray burst/supernova connection

    CERN Document Server

    Bloom, J S; Djorgovski, S G; Eichelberger, A C; Côté, P; Blakeslee, J P; Odewahn, S C; Harrison, F A; Frail, D A; Filippenko, A V; Leonard, D C; Riess, A G; Spinrad, H; Stern, D; Bunker, A J; Dey, A; Stanford, S A; Grossan, B; Perlmutter, S; Knop, R A; Hook, I M; Feroci, M

    1999-01-01

    Cosmic gamma-ray bursts (GRBs) have been firmly established as one of the most powerful phenomena in the Universe, releasing electromagnetic energy approaching the rest-mass energy of a neutron star in a few seconds. The two currently popular models for GRB progenitors are the coalescence of two compact objects (such as neutron stars or black holes) or collapse of a massive star. An unavoidable consequence of the latter model is that a bright supernovae should accompany the GRB. The emission from this supernova competes with the much brighter afterglow produced by the relativistic shock that gives rise to the GRB itself. Here we present evidence for an unusual light curve for GRB 980326 based on new optical observations. The transient brightened ~3 weeks after the burst to a flux sixty times larger than that extrapolated from the rapid decay seen at early time. Furthermore, the spectrum changed dramatically and became extremely red. We argue that the new source is the underlying supernova. If our hypothesis i...

  2. GRB 990123 Reverse and Internal Shock Flashes and Late Afterglow

    CERN Document Server

    Mészáros, P

    1999-01-01

    The prompt $(t \\siml 0.16$ days) light curve and initial 9-th magnitude optical flash from GRB 990123 can be attributed to a reverse external shock, or possibly to internal shocks. We discuss the time decay laws and spectral slopes expected under various dynamical regimes, and discuss the constraints imposed on the model by the observations, arguing that they provide strongly suggestive evidence for features beyond those in the simple standard model. The longer term afterglow behavior is discussed in the context of the forward shock, and it is argued that, if the steepening after three days is due to a jet geometry, this is likely to be due to jet-edge effects, rather than sideways expansion.

  3. GRB 030227: The first multiwavelength afterglow of an INTEGRAL GRB

    DEFF Research Database (Denmark)

    Castro-Tirado, A.J.; Gorosabel, J.; Guziy, S.

    2003-01-01

    We present multiwavelength observations of a gamma-ray burst detected by INTEGRAL (GRB 030227) between 5.3 hours and similar to1.7 days after the event. Here we report the discovery of a dim optical afterglow (OA) that would not have been detected by many previous searches due to its faintess (R...... similar to 23). This OA was seen to decline following a power law decay with index alpha(R) = - 0.95 +/- 0.16. The spectral index beta(opt/NIR) yielded - 1.25 +/- 0.14. These values may be explained by a relativistic expansion of a fireball ( with p = 2.0) in the cooling regime. We also find evidence...... for inverse Compton scattering in X-rays....

  4. Langmuir-Probe Measurements in Flowing-Afterglow Plasmas

    Science.gov (United States)

    Johnsen, R.; Shunko, E. V.; Gougousi, T.; Golde, M. F.

    1994-01-01

    The validity of the orbital-motion theory for cylindrical Langmuir probes immersed in flowing- afterglow plasmas is investigated experimentally. It is found that the probe currents scale linearly with probe area only for electron-collecting but not for ion-collecting probes. In general, no agreement is found between the ion and electron densities derived from the probe currents. Measurements in recombining plasmas support the conclusion that only the electron densities derived from probe measurements can be trusted to be of acceptable accuracy. This paper also includes a brief derivation of the orbital-motion theory, a discussion of perturbations of the plasma by the probe current, and the interpretation of plasma velocities obtained from probe measurements.

  5. Modelling extragalactic extinction through gamma-ray burst afterglows

    CERN Document Server

    Zonca, Alberto; Mulas, Giacomo; Casu, Silvia; Aresu, Giambattista

    2016-01-01

    We analyze extragalactic extinction pro?les derived through gamma-ray burst afterglows, using a dust model speci?cally constructed on the assumption that dust grains are not immutable but respond time-dependently to the local physics. Such a model includes core-mantle spherical particles of mixed chemical composition (silicate core, sp2 and sp3 carbonaceous layers), and an additional molecular component, in the form of free-flying polycyclic aromatic hydrocarbons. We fit most of the observed extinction pro?les. Failures occur for lines of sight presenting remarkable rises blueward the bump. We find a tendency in the carbon chemical structure to become more aliphatic with the galactic activity, and to some extent with increasing redshifts. Moreover, the contribution of the moleclar component to the total extinction is more important in younger objects. The results of the ?tting procedure (either successes and failures) may be naturally interpreted through an evolutionary prescription based on the carbon cycle ...

  6. Perspectives of observing the color indices of optical afterglows of gamma-ray bursts with ESA Gaia

    Science.gov (United States)

    Šimon, Vojtěch; Hudec, René; Pizzichini, Graziella

    2017-08-01

    We propose a strategy for detecting and analyzing optical afterglows (OAs) of long gamma-ray bursts (GRBs) without the need to obtain their light curves. This approach is useful for the Gaia satellite, which provides sampled optical ultra-low-dispersion spectroscopic observations of the sky. For this purpose, we show that most OAs of long GRBs display specific values of some of their color indices, representing synchrotron emission of the jet. They are stable in time during the event. These indices, which can be determined from the spectra, are very similar for the ensemble of OAs with redshift z sources (host galaxies of OAs detectable later by the large ground-based telescopes at the co-ordinates of the OA determined by Gaia) would tell us which one, among transients detected by Gaia, is a GRB OA.

  7. Shallow Decay of X-ray Afterglows in Short GRBs: Energy Injection from a Millisecond Magnetar?

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the successful launch of Swift satellite, more and more data of early X-ray afterglows from short gamma-ray bursts have been collected. Some interesting features such as unusual afterglow light curves and unexpected X-ray flares are revealed. Especially, in some cases, there is a flat segment in the X-ray afterglow light curve. Here we present a simplified model in which we believe that the flattening part is due to energy injection from the central engine. We assume that this energy injection arises from the magnetic dipole radiation of a millisecond pulsar formed after the merger of two neutron stars. We check this model with the short GRB 060313. Our numerical results suggest that energy injection from a millisecond magnetar could make part of the X-ray afterglow light curve flat.

  8. Multi-wavelength observations of afterglow of GRB 080319B and the modeling constraints

    CERN Document Server

    Pandey, S B; Jelínek, M; Kamble, Atish P; Gorosabel, J; Postigo, A de Ugarte; Prins, S; Oreiro, R; Chantry, V; Trushkin, S; Bremer, M; Winters, J M; Pozanenko, A; Krugly, Yu; Slyusarev, I; Kornienko, G; Erofeeva, A; Misra, K; Ramprakash, A N; Mohan, V; Bhattacharya, D; Volnova, A; Plá, J; Ibrahimov, M; Im, M; Volvach, A; Wijers, R A M J

    2009-01-01

    We present observations of the afterglow of GRB 080319B at optical, mm and radio frequencies from a few hours to 67 days after the burst. Present observations along with other published multi-wavelength data have been used to study the light-curves and spectral energy distributions of the burst afterglow. The nature of this brightest cosmic explosion has been explored based on the observed properties and it's comparison with the afterglow models. Our results show that the observed features of the afterglow fits equally good with the Inter Stellar Matter and the Stellar Wind density profiles of the circum-burst medium. In case of both density profiles, location of the maximum synchrotron frequency $\

  9. Ion density and dielectric breakdown in the afterglow of a high-current arc discharge

    Energy Technology Data Exchange (ETDEWEB)

    Rutgers, W.R.; Verhagen, F.C.M.; De Zeeuw, W.A.

    1984-01-01

    The ion density in the afterglow of a high-current atmospheric arc-discharge and electrical breakdown have been investigated in atomic (argon), molecular (nitrogen) and electronegative (carbon dioxide) media. From the decay with time of the ion density, effective recombination coefficients can be calculated. When the ion density is reduced to values below 2 x 10/sup 17/m/sup -3/, the afterglow plasma changes from a resistive into a dielectric medium. (J.C.R.)

  10. Escherichia coli morphological changes and lipid A removal induced by reduced pressure nitrogen afterglow exposure.

    Directory of Open Access Journals (Sweden)

    Hayat Zerrouki

    Full Text Available Lipid A is a major hydrophobic component of lipopolysaccharides (endotoxin present in the membrane of most Gram-negative bacteria, and the major responsible for the bioactivity and toxicity of the endotoxin. Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr can be used for the sterilization of surfaces and of the reusable medical instrumentation. In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow. In parallel, the time variation of the inactivation efficiency quantified by the log reduction of the initial Escherichia coli (E. coli population is correlated with morphologic changes observed on the bacteria by scanning electron microscopy (SEM for increasing afterglow exposure times. The effect of the afterglow exposure is also studied on pure lipid A and on lipid A extracted from exposed E. coli bacteria. We report that more than 60% of lipid A (pure or bacteria-extracted are lost with the used operating conditions (nitrogen flow QN2 = 1 standard liter per minute (slpm, pressure p = 5 Torr, microwave injected power PMW = 200 W, exposure time: 40 minutes. The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted lipid A. Altogether these results point out the ability of reduced pressure nitrogen afterglows to neutralize the cytotoxic components in Gram-negative bacteria.

  11. Afterglows from Jetted Gamma-Ray-Burst Remnant: Does the Light Curve Break?

    Institute of Scientific and Technical Information of China (English)

    HUANG Yong-Feng; DAI Zi-Gao; LU Tan

    2000-01-01

    Afterglows from jetted gamma-ray bursts are generally believed to be characterized by an obvious break in the light curve at the relativistic stage. We show that it is not the case. However, an obvious break does exist at the transition from the relativistic phase to the non-relativistic phase. Although this break itself is parameter dependent, afterglows from jetted remnant are uniformly characterized by a quick decay during the non-relativistic phase.

  12. Testing the fireball/blastwave model by monitoring afterglows from soft gamma repeaters

    OpenAIRE

    Huang, Y. F.

    2005-01-01

    The popular fireball/blastwave model of classical gamma-ray bursts is applied to soft gamma-ray bursts. It is found that X-ray afterglows from strong events may be above their quiescent levels for 40 -- 400 seconds. Optical afterglows may also be detectable. By monitoring the three repeaters, we will have an ideal way to check the fireball/blastwave model.

  13. Escherichia coli Morphological Changes and Lipid A Removal Induced by Reduced Pressure Nitrogen Afterglow Exposure

    Science.gov (United States)

    Zerrouki, Hayat; Rizzati, Virginie; Bernis, Corinne; Nègre-Salvayre, Anne; Sarrette, Jean Philippe; Cousty, Sarah

    2015-01-01

    Lipid A is a major hydrophobic component of lipopolysaccharides (endotoxin) present in the membrane of most Gram-negative bacteria, and the major responsible for the bioactivity and toxicity of the endotoxin. Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr) can be used for the sterilization of surfaces and of the reusable medical instrumentation. In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow. In parallel, the time variation of the inactivation efficiency quantified by the log reduction of the initial Escherichia coli (E. coli) population is correlated with morphologic changes observed on the bacteria by scanning electron microscopy (SEM) for increasing afterglow exposure times. The effect of the afterglow exposure is also studied on pure lipid A and on lipid A extracted from exposed E. coli bacteria. We report that more than 60% of lipid A (pure or bacteria-extracted) are lost with the used operating conditions (nitrogen flow QN2 = 1 standard liter per minute (slpm), pressure p = 5 Torr, microwave injected power PMW = 200 W, exposure time: 40 minutes). The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted) lipid A. Altogether these results point out the ability of reduced pressure nitrogen afterglows to neutralize the cytotoxic components in Gram-negative bacteria. PMID:25837580

  14. Temporal Evolution of the Gamma-ray Burst Afterglow Spectrum for an Observer: GeV-TeV Synchrotron Self-Compton Light Curve

    Science.gov (United States)

    Fukushima, Takuma; To, Sho; Asano, Katsuaki; Fujita, Yutaka

    2017-08-01

    We numerically simulate the gamma-ray burst (GRB) afterglow emission with a one-zone time-dependent code. The temporal evolutions of the decelerating shocked shell and energy distributions of electrons and photons are consistently calculated. The photon spectrum and light curves for an observer are obtained taking into account the relativistic propagation of the shocked shell and the curvature of the emission surface. We find that the onset time of the afterglow is significantly earlier than the previous analytical estimate. The analytical formulae of the shock propagation and light curve for the radiative case are also different from our results. Our results show that even if the emission mechanism is switching from synchrotron to synchrotron self-Compton, the gamma-ray light curves can be a smooth power law, which agrees with the observed light curve and the late detection of a 32 GeV photon in GRB 130427A. The uncertainty of the model parameters obtained with the analytical formula is discussed, especially in connection with the closure relation between spectral index and decay index.

  15. The afterglow characteristics of xenon pulsed plasma for mercury-free fluorescent lamps

    Science.gov (United States)

    Jinno, Masafumi; Kurokawa, Hisayoshi; Aono, Masaharu; Ninomiya, Hideki

    2000-03-01

    In this study, the spectroscopic characteristics of radiations from xenon pulsed plasma are measured experimentally as a study on a mercury-free fluorescent lamp. Each radiation waveform has two peaks and they vary according to the inner diameter of lamp and the pressure of xenon as follows: (a) As the inner diameter of lamps increases, the afterglow radiation, that is the second peak, decays faster. (b) As the xenon pressure increases the first peak of radiation just after the start of discharge decreases and the afterglow increases. The characteristics of afterglow are explained by the rate equation of metastable xenon atoms Xem, and its coefficients are determined through the experimental results. This equation shows that in order to obtain intense phosphor afterglow, i.e. strong radiation of xenon excimer, high pressure of xenon and large lamp diameter are desirable. Moreover, high pressure of xenon brings fast decay of afterglow. Then the afterglow radiation has no overlap on the first peak of next discharge at a high frequency. Consequently, higher pressure of xenon and large lamp diameter are desirable for high intensity and high efficacy for xenon fluorescent lamps.

  16. Comprehensive multi-wavelength modelling of the afterglow of GRB050525A

    CERN Document Server

    Resmi, L; Jóhannesson, G; Castro-Tirado, A J; Gorosabel, J; Jelínek, M; Bhattacharya, D; Kubánek, P; Anupama, G C; Sota, A; Sahu, D K; Postigo, A de Ugarte; Pandey, S B; Sánchez-Ramírez, R; Bremer, M; Sagar, R

    2012-01-01

    The Swift era has posed a challenge to the standard blast-wave model of Gamma Ray Burst (GRB) afterglows. The key observational features expected within the model are rarely observed, such as the achromatic steepening (`jet-break') of the light curves. The observed afterglow light curves showcase additional complex features requiring modifications within the standard model. Here we present optical/NIR observations, millimeter upper limits and comprehensive broadband modelling of the afterglow of the bright GRB 0505025A, detected by Swift. This afterglow cannot be explained by the simplistic form of the standard blast-wave model. We attempt modelling the multi-wavelength light curves using (i) a forward-reverse shock model, (ii) a two-component outflow model and (iii) blast-wave model with a wind termination shock. The forward-reverse shock model cannot explain the evolution of the afterglow. The two component model is able to explain the average behaviour of the afterglow very well but cannot reproduce the fl...

  17. Suppression of afterglow in CsI:Tl by co doping with Eu{sup 2+}-II: Theoretical model

    Energy Technology Data Exchange (ETDEWEB)

    Bartram, R.H. [Department of Physics, University of Connecticut, Storrs, CT 06269-3046 (United States); Kappers, L.A. [Department of Physics, University of Connecticut, Storrs, CT 06269-3046 (United States); Hamilton, D.S. [Department of Physics, University of Connecticut, Storrs, CT 06269-3046 (United States); Lempicki, A. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States); Brecher, C. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States)]. E-mail: cbrecher@rmdinc.com; Glodo, J. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States); Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Gaysinskiy, V. [Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States); Ovechkina, E.E. [Radiation Monitoring Devices (RMD) Inc., 44 Hunt Street, Watertown, MA 02472 (United States)

    2006-03-15

    The mechanism for afterglow suppression in codoped CsI:Tl,Eu reported in the preceding paper was investigated by combined radioluminescence and thermoluminescence experiments. Model rate equations informed by these experiments were employed to simulate afterglow. It was found that codoping with europium introduces deep electron traps, with room-temperature glow peaks, that effectively scavenge the electrons from shallow traps associated with thallium, thus suppressing afterglow in the time domain of tens of milliseconds.

  18. Study of GRB Light-curve Decay Indices in the Afterglow Phase

    Science.gov (United States)

    Del Vecchio, Roberta; Dainotti, Maria Giovanna; Ostrowski, Michał

    2016-09-01

    In this work, we study the distribution of temporal power-law decay indices, α, in the gamma-ray burst (GRB) afterglow phase, fitted for 176 GRBs (139 long GRBs, 12 short GRBs with extended emission, and 25 X-ray flashes) with known redshifts. These indices are compared with the temporal decay index, α W , derived with the light-curve fitting using the Willingale et al. model. This model fitting yields similar distributions of α W to the fitted α, but for individual bursts a difference can be significant. Analysis of (α, L a ) distribution, where L a is the characteristic luminosity at the end of the plateau, reveals only a weak correlation of these quantities. However, we discovered a significant regular trend when studying GRB α values along the Dainotti et al. correlation between L a and the end time of the plateau emission in the rest frame, {T}a* , hereafter LT correlation. We note a systematic variation of the α parameter distribution with luminosity for any selected {T}a* . We analyze this systematics with respect to the fitted LT correlation line, expecting that the presented trend may allow us to constrain the GRB physical models. We also attempted to use the derived correlation of α ({T}a) versus {L}a({T}a) to diminish the luminosity scatter related to the variations of α along the LT distribution, a step forward in the effort of standardizing GRBs. A proposed toy model accounting for this systematics applied to the analyzed GRB distribution results in a slight increase of the LT correlation coefficient.

  19. High energy gamma-ray emission from Gamma-Ray Bursts -- before GLAST

    CERN Document Server

    Fan, Yi-Zhong

    2008-01-01

    Gamma-ray bursts (GRBs) are short and intense emission of soft gamma-rays, which have fascinated astronomers and astrophysicists since their unexpected discovery in 1960s. The X-ray/optical/radio afterglow observations confirm the cosmological origin of GRBs, support the fireball model, and imply a long-activity of the central engine. The high energy gamma-ray emission (>20 MeV) from GRBs is particularly important because they shed some lights on the radiation mechanisms and can help us to constrain the physical processes giving rise to the early afterglows. In this work, we review observational and theoretical studies of the high energy emission from GRBs. Special attention is given to the expected high energy emission signatures accompanying the canonical early-time X-ray afterglow that was observed by the Swift X-ray Telescope. We also discuss the detection prospect of the upcoming GLAST satellite and the current ground-based Cerenkov detectors.

  20. Discovery of a Very Bright and Intrinsically Very Luminous, Strongly Lensed Lyα Emitting Galaxy at z = 2.82 in the BOSS Emission-Line Lens Survey

    Science.gov (United States)

    Marques-Chaves, Rui; Pérez-Fournon, Ismael; Shu, Yiping; Martínez-Navajas, Paloma I.; Bolton, Adam S.; Kochanek, Christopher S.; Oguri, Masamune; Zheng, Zheng; Mao, Shude; Montero-Dorta, Antonio D.; Cornachione, Matthew A.; Brownstein, Joel R.

    2017-01-01

    We report the discovery of a very bright (r = 20.16), highly magnified, and yet intrinsically very luminous Lyα emitter (LAE) at z=2.82. This system comprises four images in the observer plane with a maximum separation of ∼ 6\\prime\\prime and it is lensed by a z=0.55 massive early-type galaxy. It was initially identified in the Baryon Oscillation Spectroscopic Survey Emission-Line Lens Survey for GALaxy-Lyα EmitteR sYstems survey, and follow-up imaging and spectroscopic observations using the Gran Telescopio Canarias and William Herschel Telescope confirmed the lensing nature of this system. A lens model using a singular isothermal ellipsoid in an external shear field reproduces the main features of the system quite well, yielding an Einstein radius of 2.″95 ± 0.″10, and a total magnification factor for the LAE of 8.8 ± 0.4. This LAE is one of the brightest and most luminous galaxy–galaxy strong lenses known. We present initial imaging and spectroscopy showing the basic physical and morphological properties of this lensed system. Based on observations made with the Gran Telescopio Canarias (GTC) and William Herschel Telescope (WHT), in the Spanish Observatorio del Roque de los Muchachos of the IAC, under Directors Discretionary Time (DDT programs IDs: GTC2016-054 and DDT2016-077).

  1. The afterglow and the host galaxy of GRB 011211

    Science.gov (United States)

    Jakobsson, P.; Hjorth, J.; Fynbo, J. P. U.; Gorosabel, J.; Pedersen, K.; Burud, I.; Levan, A.; Kouveliotou, C.; Tanvir, N.; Fruchter, A.; Rhoads, J.; Grav, T.; Hansen, M. W.; Michelsen, R.; Andersen, M. I.; Jensen, B. L.; Pedersen, H.; Thomsen, B.; Weidinger, M.; Bhargavi, S. G.; Cowsik, R.; Pandey, S. B.

    2003-09-01

    We present optical, near-infrared, and X-ray observations of the optical afterglow (OA) of the X-ray rich, long-duration gamma-ray burst GRB 011211. Hubble Space Telescope (HST) data obtained 14, 26, 32, and 59 days after the burst, show the host galaxy to have a morphology that is fairly typical of blue galaxies at high redshift. We measure its magnitude to be R = 24.95 +/- 0.11. We detect a break in the OA R-band light curve which is naturally accounted for by a collimated outflow geometry. By fitting a broken power-law to the data we find a best fit with a break 1.56 +/- 0.02 days after the burst, a pre-break slope of alpha1 = -0.95 +/- 0.02, and a post-break slope of alpha2 = -2.11 +/- 0.07. The UV-optical spectral energy distribution (SED) around 14 hours after the burst is best fit with a power-law with index beta = -0.56 +/- 0.19 reddened by an SMC-like extinction law with a modest AV = 0.08 +/- 0.08 mag. By comparison, from the XMM-Newton X-ray data at around the same time, we find a decay index of alphaX = -1.62 +/- 0.36 and a spectral index of betaX = -1.21+0.10-0.15. Interpolating between the UV-optical and X-ray implies that the cooling frequency is located close to ~ 1016 Hz in the observer frame at the time of the observations. We argue, using the various temporal and spectral indices above, that the most likely afterglow model is that of a jet expanding into an external environment that has a constant mean density rather than a wind-fed density structure. We estimate the electron energy index for this burst to be p ~ 2.3. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden. Based on observations made with ESO Telescopes at the Paranal Observatory by GRACE under programme ID 69.D-0701. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the

  2. What can we learn from "internal plateaus"? The peculiar afterglow of GRB 070110

    Science.gov (United States)

    Beniamini, P.; Mochkovitch, R.

    2017-09-01

    Context. The origin of the prompt emission of gamma-ray bursts is highly debated. Proposed scenarios involve various dissipation processes (shocks, magnetic reconnection, and inelastic collisions) above or below the photosphere of an ultra-relativistic outflow. Aims: We search for observational features that could help to favour one scenario over the others by constraining the dissipation radius, the magnetization of the outflow, or by indicating the presence of shocks. Bursts showing peculiar behaviours can emphasize the role of a specific physical ingredient, which becomes more apparent under certain circumstances. Methods: We study GRB 070110, which exhibited several remarkable features during its early afterglow; i.e. a very flat plateau terminated by an extremely steep drop and immediately followed by a bump. We modelled the plateau as the photospheric emission from a long-lasting outflow of moderate Lorentz factor (Γ 20), which lags behind an ultra-relativistic (Γ > 100) ejecta that is responsible for the prompt emission. We computed the dissipation of energy in the forward and reverse shocks resulting from the deceleration of this ejecta by the external medium (uniform or stellar wind). Results: We find that photospheric emission from the long-lasting outflow can account for the plateau properties (luminosity and spectrum) assuming that some dissipation takes place in the flow. The geometrical timescale at the photospheric radius is so short that the observed decline at the end of the plateau likely corresponds to the actual shutdown of the activity in the central engine. The bump that follows results from the power dissipated in the reverse shock, which develops when the material making the plateau catches up with the initially fast shell in front, after the fast shell has decelerated. Conclusions: The proposed interpretation suggests that the prompt phase results from dissipation above the photosphere while the plateau has a photospheric origin. If the

  3. Radio transient following FRB 150418: afterglow or coincident AGN flare?

    CERN Document Server

    Li, Ye

    2016-01-01

    Recently, Keane et al. reported the discovery of a fading radio transient following FRB 150418, and interpreted it as the afterglow of the FRB. Williams \\& Berger, on the other hand, suggested that the radio transient is analogous to a group of variable radio sources, so that it could be a coincident AGN flare in the observational beam of the FRB. A new observation with VLA showed a re-brightening, which is consistent with the AGN picture. Here, using the radio survey data of Ofek et al., we statistically examine the chance coincidence probability to produce an event like the FRB 150418 transient. We find that the probabilities to produce a variable radio transient with at least the same variability amplitude and signal-to-noise ratio as the FRB 150415 transient, without and with the VLA point, are $P_1 \\sim 6 \\times 10^{-4}$ and $P_1 \\sim 2 \\times 10^{-3}$, respectively. In addition, the chance probability to have a fading transient detected following a random time (FRB time) is less than $P_2 \\sim 10^{-...

  4. Testing GRB models with the strange afterglow of GRB 090102

    CERN Document Server

    Gendre, B; Palazzi, E; Kruhler, T; Covino, S; Afonso, P; Antonelli, L A; Atteia, J L; D'Avanzo, P; Boër, M; Greiner, J; Klose, S

    2009-01-01

    We present the observations of the afterglow of gamma-ray burst GRB 090102. We use optical data taken by the TAROT, REM, GROND, Palomar and NOT telescopes, and X-ray data taken by the XRT instrument on board the Swift spacecraft. This event features an unusual light curve. In X-rays, it presents a very monotonic decrease with no hint of temporal break from 0.005 to 6 days after the burst. In optical, the light curve presents a flattening after 1 ks. Before this break, the optical light curve is steeper than the X-ray one. In optical, no further break is observed up to 10 days after the burst. We tried to explain these observations in light of the standard fireball model, but we failed to do so. We then investigated several other models, like the cannonball model. We find that the explanation of the broad band data by any model requires a strong fine tuning when taking into account both optical and X-ray bands.

  5. The Molecular Hydrogen Deficit in Gamma-Ray Burst Afterglows

    CERN Document Server

    Whalen, Daniel; Heger, Alexander; Tumlinson, Jason

    2008-01-01

    Recent analysis of five gamma-ray burst (GRB) afterglow spectra reveal the absence of molecular hydrogen absorption lines, a surprising result in light of their large neutral hydrogen column densities and the detection of H$_2$ in similar, more local star-forming regions like 30 Doradus in the LMC. Observational evidence further indicates that the bulk of the neutral hydrogen column in these sight lines lies 100 pc beyond the progenitor and that H$_2$ was absent prior to the burst, suggesting that direct flux from the star, FUV background fields, or both suppressed its formation. We present one-dimensional radiation hydrodynamical models of GRB host galaxy environments, including self-consistent radiative transfer of both ionizing and Lyman-Werner photons, nine-species primordial chemistry with dust formation of H$_2$, and dust extinction of UV photons. We find that a single GRB progenitor is sufficient to ionize neutral hydrogen to distances of 50 - 150 pc but that a galactic Lyman-Werner background is requi...

  6. The afterglow and the host galaxy of GRB 011211

    CERN Document Server

    Jakobsson, P; Fynbo, J P U; Gorosabel, J; Pedersen, K; Burud, I; Levan, A J; Kouveliotou, C; Tanvir, N R; Fruchter, A S; Rhoads, J; Grav, T; Hansen, M W; Michelsen, R; Andersen, M I; Jensen, B L; Pedersen, H; Thomsen, B; Weidinger, M; Bhargavi, S G; Cowsik, R; Pandey, S B

    2003-01-01

    We present optical, near-infrared, and X-ray observations of the optical afterglow (OA) of the X-ray rich, long-duration gamma-ray burst GRB 011211. Hubble Space Telescope (HST) data obtained 14, 26, 32, and 59 days after the burst, show the host galaxy to have a morphology that is fairly typical of blue galaxies at high redshift. We measure its magnitude to be R = 24.95 +/- 0.11. We detect a break in the OA R-band light curve which is naturally accounted for by a collimated outflow geometry. By fitting a broken power-law to the data we find a best fit with a break 1.56 +/- 0.02 days after the burst, a pre-break slope of alpha_1 = -0.95 +/- 0.02, and a post-break slope of alpha_2 = -2.11 +/- 0.07. The UV-optical spectral energy distribution (SED) around 14 hours after the burst is best fit with a power-law with index beta = -0.56 +/- 0.19 reddened by an SMC-like extinction law with a modest A_V = 0.08 +/- 0.08 mag. By comparison, from the XMM-Newton X-ray data at around the same time, we find a decay index of...

  7. Fireballs and cannonballs confront the afterglow of GRB 991208

    CERN Document Server

    Dado, S; De Rújula, Alvaro; Dado, Shlomo; Dar, Arnon; Rujula, Alvaro De

    2003-01-01

    Galama et al. have recently reported their follow-up measurements of the radio afterglow (AG) of the Gamma Ray Burst (GRB) 991208, up to 293 days after burst, and their reanalysis of the broad-band AG, in the framework of standard fireball models. They advocate a serious revision of their prior analysis and conclusions, based on optical data and on their earlier observations during the first two weeks of the AG. We comment on their work and fill a lacuna: these authors have overlooked the possibility of comparing their new data to the available predictions of the cannonball (CB) model, based --like their incorrect predictions-- on the first round of data. The new data are in good agreement with these CB-model predictions. This is in spite of the fact that, in comparison to the fireball models, the CB model is much simpler, much more predictive, has many fewer parameters, practically no free choices... and it describes well --on a universal basis-- all the measured AGs of GRBs of known redshift.

  8. How Bad or Good Are the External Forward Shock Afterglow Models of Gamma-Ray Bursts?

    Science.gov (United States)

    Wang, Xiang-Gao; Zhang, Bing; Liang, En-Wei; Gao, He; Li, Liang; Deng, Can-Min; Qin, Song-Mei; Tang, Qing-Wen; Kann, D. Alexander; Ryde, Felix; Kumar, Pawan

    2015-07-01

    The external forward shock models have been the standard paradigm to interpret the broadband afterglow data of gamma-ray bursts (GRBs). One prediction of the models is that some afterglow temporal breaks at different energy bands should be achromatic; that is, the break times should be the same in different frequencies. Multiwavelength observations in the Swift era have revealed chromatic afterglow behaviors at least in some GRBs, casting doubts on the external forward shock origin of GRB afterglows. In this paper, using a large sample of GRBs with both X-ray and optical afterglow data, we perform a systematic study to address the question: how bad or good are the external forward shock models? Our sample includes 85 GRBs up to 2014 March with well-monitored X-ray and optical light curves. Based on how well the data abide by the external forward shock models, we categorize them into five grades and three samples. The first two grades (Grade I and II) include 45 of 85 GRBs. They show evidence of, or are consistent with having, an achromatic break. The temporal and spectral behaviors in each afterglow segment are consistent with the predictions (the “closure relations”) of the forward shock models. These GRBs are included in the Gold sample. The next two grades (Grade III and IV) include 37 of 85 GRBs. They are also consistent with having an achromatic break, even though one or more afterglow segments do not comply with the closure relations. These GRBs are included in the Silver sample. Finally, Grade V (3/85) shows direct evidence of chromatic behaviors, suggesting that the external shock models are inconsistent with the data. These are included in the Bad sample. We further perform statistical analyses of various observational properties (temporal index α, spectral index β, break time tb) and model parameters (energy injection index q, electron spectral index p, jet opening angle {θ }j, radiative efficiency ηγ, and so on) of the GRBs in the Gold sample

  9. Short GRB 130603B: Discovery of a jet break in the optical and radio afterglows, and a mysterious late-time X-ray excess

    Energy Technology Data Exchange (ETDEWEB)

    Fong, W.; Berger, E.; Margutti, R.; Chornock, R.; Migliori, G.; Zauderer, B. A.; Lunnan, R.; Laskar, T. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Metzger, B. D. [Department of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Foley, R. J. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801 (United States); Desch, S. J. [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States); Meech, K. J.; Sonnett, S. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Dickey, C.; Hedlund, A. [Pomona College, 610 N. College Ave., Claremont, CA 91711 (United States); Harding, P. [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106-7215 (United States)

    2014-01-10

    We present radio, optical/NIR, and X-ray observations of the afterglow of the short-duration Swift and Konus-Wind GRB 130603B, and uncover a break in the radio and optical bands at ≈0.5 day after the burst, best explained as a jet break with an inferred jet opening angle of ≈4°-8°. GRB 130603B is only the third short GRB with a radio afterglow detection to date, and represents the first time that a jet break has been evident in the radio band. We model the temporal evolution of the spectral energy distribution to determine the burst explosion properties and find an isotropic-equivalent kinetic energy of ≈(0.6-1.7) × 10{sup 51} erg and a circumburst density of ≈5 × 10{sup –3}-30 cm{sup –3}. From the inferred opening angle of GRB 130603B, we calculate beaming-corrected energies of E {sub γ} ≈ (0.5-2) × 10{sup 49} erg and E {sub K} ≈ (0.1-1.6) × 10{sup 49} erg. Along with previous measurements and lower limits we find a median opening angle of ≈10°. Using the all-sky observed rate of 10 Gpc{sup –3} yr{sup –1}, this implies a true short GRB rate of ≈20 yr{sup –1} within 200 Mpc, the Advanced LIGO/VIRGO sensitivity range for neutron star binary mergers. Finally, we uncover evidence for significant excess emission in the X-ray afterglow of GRB 130603B at ≳ 1 day and conclude that the additional energy component could be due to fall-back accretion or spin-down energy from a magnetar formed following the merger.

  10. Machine Learning Search for Gamma-Ray Burst Afterglows in Optical Images

    Science.gov (United States)

    Topinka, M.

    2016-06-01

    Thanks to the advances in robotic telescopes, time domain astronomy leads to a large number of transient events detected in images every night. Data mining and machine learning tools used for object classification are presented. The goal is to automatically classify transient events for both further follow-up by a larger telescope and for statistical studies of transient events. Special attention is given to the identification of gamma-ray burst afterglows. Machine learning techniques are used to identify GROND gamma-ray burst afterglow among the astrophysical objects present in the SDSS archival images based on the g'-r', r'-i' and i'-z' color indices. The performance of the support vector machine, random forest and neural network algorithms is compared. A joint meta-classifier, built on top of the individual classifiers, can identify GRB afterglows with the overall accuracy of ≳ 90%.

  11. Machine Learning Search for Gamma-Ray Burst Afterglows in Optical Surveys

    CERN Document Server

    Topinka, Martin

    2015-01-01

    Thanks to the advances in robotic telescopes, the time domain astronomy leads to a large number of transient events detected in images every night. Data mining and machine learning tools used for object classification are presented. The goal is to automatically classify transient events for both further follow-up by a larger telescope and for statistical studies of transient events. A special attention is given to the identification of gamma-ray burst afterglows. Machine learning techniques is used to identify GROND gamma-ray burst afterglow among the astrophysical objects present in the SDSS archival images based on the $g'-r'$, $r'-i'$ and $i'-z'$ colour indices. The performance of the support vector machine, random forest and neural network algorithms is compared. A joint meta-classifier, built on top of the individual classifiers, can identify GRB afterglows with the overall accuracy of $\\gtrsim 90\\%$.

  12. Constraints on an Optical Afterglow and on Supernova Light Following the Short Burst GRB 050813

    Science.gov (United States)

    Ferrero, P.; Sanchez, S. F.; Kann, D. A.; Klose, S.; Greiner, J.; Gorosabel, J.; Hartmann, D. H.; Henden, A. A.; Moller, P.; Palazzi, E.; Rau, A.; Stecklum, B.; Castro-Tirado, A. J.; Fynbok J. P. U.; Hjorth, J.; Jakobsson, P.; Kouveliotou, C.; Masetti, N.; Pian, E.; Tanvir, N. R.; Wijers, R. A. M. J.

    2006-01-01

    We report early follow-up observations of the error box of the short burst 050813 using the telescopes at Calar Alto and at Observatorio Sierra Nevada (OSN), followed by deep VLT/FORS2 I-band observations obtained under very good seeing conditions 5.7 and 11.7 days after the event. No evidence for a GRB afterglow was found in our Calar Alto and OSN data, no rising supernova component was detected in our FORS2 images. A potential host galaxy can be identified in our FORS2 images, even though we cannot state with certainty its association with GRB 050813. IN any case, the optical afterglow of GRB 050813 was very faint, well in agreement with what is known so far about the optical properties of afterglows of short bursts. We conclude that all optical data are not in conflict with the interpretation that GRB 050813 was a short burst.

  13. A tunneling model for afterglow suppression in CsI:Tl,Sm scintillation materials

    Energy Technology Data Exchange (ETDEWEB)

    Kappers, L.A., E-mail: lawrence.kappers@uconn.ed [Department of Physics, University of Connecticut, 2152 Hillside Road, Storrs, CT 06269-3046 (United States); Bartram, R.H.; Hamilton, D.S. [Department of Physics, University of Connecticut, 2152 Hillside Road, Storrs, CT 06269-3046 (United States); Lempicki, A.; Brecher, C. [ALEM Associates, 303 Commonwealth Avenue, Boston, MA 02115 (United States); Gaysinskiy, V.; Ovechkina, E.E.; Thacker, S.; Nagarkar, V.V. [Radiation Monitoring Devices (RMD) Inc., 44 Hunt St., Watertown, MA 02472 (United States)

    2010-03-15

    Combined radioluminescence, afterglow and thermoluminescence experiments on single-crystal samples of co-doped CsI:Tl,Sm suggest that samarium electron traps scavenge electrons from thallium traps and that electrons subsequently released by samarium recombine non-radiatively with trapped holes, thus suppressing afterglow. Experiments on single crystals support the inference that electrons tunnel freely between samarium ions and are trapped preferentially as substitutional Sm{sup +} near V{sub KA}(Tl{sup +}) centers where non-radiative recombination is the rate-limiting step. Afterglow in microcolumnar films of CsI:Tl,Sm is enhanced by inhomogeneities which impede tunneling between samarium ions, but is partly suppressed by annealing.

  14. X-ray excited ZnS:Cu,Co afterglow nanoparticles for photodynamic activation

    Science.gov (United States)

    Ma, Lun; Zou, Xiaoju; Bui, Brian; Chen, Wei; Song, Kwang Hyun; Solberg, Timothy

    2014-07-01

    Copper and cobalt co-doped ZnS (ZnS:Cu,Co) afterglow nanoparticles were conjugated to photosensitizer tetrabromorhodamine-123 (TBrRh123) and efficient energy transfer from the nanoparticles to TBrRh123 was observed. In addition to their X-ray excited luminescence, the ZnS:Cu,Co nanoparticles also show long lasting afterglow, which continuously serve as a light source for photodynamic therapy (PDT) activation. Compared to TBrRh123 or ZnS:Cu,Co alone, the ZnS:Cu,Co-TBrRh123 conjugates show low dark toxicity but high X-ray induced toxicity to human prostate cancer cells. The results indicate that the ZnS:Cu,Co afterglow nanoparticles have a good potential for PDT activation.

  15. A Detailed Study on the Equal Arrival Time Surface Effect in Gamma-Ray Burst Afterglows

    Institute of Scientific and Technical Information of China (English)

    Yong-Feng Huang; Ye Lu; Anna Yuen Lam Wong; Kwong Sang Cheng

    2007-01-01

    Due to the relativistic motion of gamma-ray burst remnant and its deceleration in the circumburst medium,the equal arrival time surfaces at any moment are not spherical,rather,they are distorted ellipsoids.This will leave some imprints in the afterglows.We study the effect of equal arrival time surfaces numerically for various circumstances,i.e., isotropic fireballs,collimated jets,density jumps and energy injection events.For each case,a direct comparison is made between including and not including the effect.For isotropic fireballs and jets viewed on axis,the effect slightly hardens the spectra and postpones the peak time of the afterglows,but does not change the shapes of the spectra and light curves significantly.In the cases of a density jump or an energy injection,the effect smears out the variations in the afterglows markedly.

  16. Perspective on Afterglows: Numerically Computed Views, Lightcurves and the Analysis of Homogeneous and Structured Jets with Lateral Expansion

    CERN Document Server

    Salmonson, J D

    1993-01-01

    Herein I present numerical calculations of lightcurves of homogeneous and structured afterglows with various lateral expansion rates as seen from any vantage point. Such calculations allow for direct simulation of observable quantities for complex afterglows with arbitrary energy distributions and lateral expansion paradigms. A simple, causal model is suggested for lateral expansion of the jet as it evolves; namely, that the lateral expansion kinetic energy derives from the forward kinetic energy. As such the homogeneous jet model shows that lateral expansion is important at all times in the afterglow evolution and that analytical scaling laws do a poor job at describing the afterglow decay before and after the break. In particular, I find that lateral expansion does not cause a break in the lightcurve as had been predicted. A primary purpose of this paper is to study structured afterglows, which do a good job of reproducing global relationships and correlations in the data and thus suggest the possibility of...

  17. Advances in flowing afterglow and selected-ion flow tube techniques

    Science.gov (United States)

    Squires, Robert R.

    1992-09-01

    New developments in flowing afterglow and selected-ion flow tube (SIFT) techniques are briefly reviewed. Particular emphasis is given to the new chemical and physical information that can be obtained with use of the tandem flowing afterglow-triple quadrupole apparatus developed in the author's laboratory. Several outstanding recent achievements in the design and utilization of flowing afterglow and SIFT instruments in other laboratories are briefly highlighted that illustrate the power and flexibility of flow-tube-based methods. These include isotope tracer experiments with the tandem flowing afterglow-SIFT instrument in Boulder, studies of large molecular cluster ions with the variable temperature facility at Penn State, and gas-phase metal ion reactions with the laser ablation/fast flow reactor in Madison. Recent applications of the flowing afterglow-triple quadrupole instrument in our laboratory have made use of collision-induced dissociation (CID) as a tool for synthesizing novel ions and for obtaining new thermo-chemical information from threshold energy measurements. Collision-induced decar☐ylation of organic car☐ylate ions provides access to a variety of unusual and highly basic carbanions that cannot be generated with conventional ion sources. The formation and properties of saturated alkyl ions and studies of gas-phase reactions of the methyl anion are briefly described. We have developed a new method for carrying out "preparative CID" in a flowing afterglow with use of a mini-drift tube; some recent applications of this new ion source are presented. Measurement of CID thresholds for simple cleavage reactions of thermalized ions can provide accurate measures of bond strengths, gas-phase acidities and basicities, and heats of formation for ions and reactive neutral species. Applications of this approach in the thermochemical characterization of carbenes, benzynes and biradicals are described. Future prospects for the continued development of flow

  18. Production of Heavy Ion Beams by Operating Serse in DC Mode and Afterglow Mode

    CERN Document Server

    Gammino, S; Celona, L; Girard, A; Hitz, D; Melin, G

    2000-01-01

    The superconducting ECR ion source SERSE is going to be coupled to a 28 GHz generator, in order to achieve higher current of intermediate and high charge states of heavy ions. Some preliminary tests have been carried out to $9 demonstrate the capability to produce currents of heavy ion beams in the order of hundreds emA in dc mode and afterglow mode. In particular, the latter tests in afterglow mode ùay play a relevant role in the design of the new source $9 for the LHC heavy ion injector.

  19. Cylindrical Jet-Wind Interaction Model of Gamma-Ray Burst Afterglows

    Institute of Scientific and Technical Information of China (English)

    Hai-Tao Ma; Yong-Feng Huang; Zi-Gao Dai; Tan Lu

    2003-01-01

    Observations on relativistic jets in radio galaxies, active galactic nuclei,and "microquasars" revealed that many of these outflows are cylindrical, not coni-cal. So it is worthwhile to investigate the evolution of cylindrical jets in gamma-raybursts. We discuss afterglows from cylindrical jets in a wind environment. Numeri-cal results as well as analytic solutions in some special cases are presented. Our lightcurves are steeper compared to those in the homogeneous interstellar medium case,carefully considered by Cheng, Huang & Lu. We conclude that some afterglows,used to be interpreted as isotropic fireballs in a wind environment, can be fitted aswell by cylindrical jets interacting with a wind.

  20. MAGNETICALLY DRIVEN WINDS FROM DIFFERENTIALLY ROTATING NEUTRON STARS AND X-RAY AFTERGLOWS OF SHORT GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, Daniel M.; Ciolfi, Riccardo; Rezzolla, Luciano [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, D-14476 Potsdam-Golm (Germany)

    2014-04-10

    Besides being among the most promising sources of gravitational waves, merging neutron star binaries also represent a leading scenario to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations have revealed a large subclass of SGRBs with roughly constant luminosity in their X-ray afterglows, lasting 10-10{sup 4} s. These features are generally taken as evidence of a long-lived central engine powered by the magnetic spin-down of a uniformly rotating, magnetized object. We propose a different scenario in which the central engine powering the X-ray emission is a differentially rotating hypermassive neutron star (HMNS) that launches a quasi-isotropic and baryon-loaded wind driven by the magnetic field, which is built-up through differential rotation. Our model is supported by long-term, three-dimensional, general-relativistic, and ideal magnetohydrodynamic simulations, showing that this isotropic emission is a very robust feature. For a given HMNS, the presence of a collimated component depends sensitively on the initial magnetic field geometry, while the stationary electromagnetic luminosity depends only on the magnetic energy initially stored in the system. We show that our model is compatible with the observed timescales and luminosities and express the latter in terms of a simple scaling relation.

  1. Spectral Softening in X-ray Afterglow of GRB 130925A as Predicted by Dust Scattering Model

    CERN Document Server

    Zhao, Yi-Nan

    2014-01-01

    Gamma-ray bursts (GRBs) usually occurs in a dense star-forming region with massive circum-burst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences, and sometimes can dominate the X-ray afterglow. In most of the previous studies, only Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius $a\\leq 0.1\\,{\\rm \\mu m}$) in the diffuse interstellar medium. When the size of the grains may significantly increase as in a more dense region where GRBs would occur, the RG approximation may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculat...

  2. Magnetically driven winds from differentially rotating neutron stars and X-ray afterglows of short gamma-ray bursts

    CERN Document Server

    Siegel, Daniel M; Rezzolla, Luciano

    2014-01-01

    Besides being among the most promising sources of gravitational waves, merging neutron-star binaries also represent a leading scenario to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations have revealed a large subclass of SGRBs with roughly constant luminosity in their X-ray afterglows lasting 10-10^4 s. These features are generally taken as evidence for a long-lived central engine powered by the magnetic spin-down of a uniformly rotating magnetized object. We propose a different scenario in which the central engine powering the X-ray emission is a differentially rotating hypermassive neutron star (HMNS) that launches a quasi-isotropic and baryon-loaded wind driven by the magnetic field built-up through differential rotation. Our model is supported by long-term, three-dimensional, general-relativistic and ideal magnetohydrodynamic simulations showing that this isotropic emission is a very robust feature. For a given HMNS, the presence of a collimated component depends sensitivel...

  3. Influence of ambient air on the flowing afterglow of an atmospheric pressure Ar/O2 radiofrequency plasma

    CERN Document Server

    Duluard, C Y; Hubert, J; Reniers, F

    2016-01-01

    The influence of ambient air on the flowing afterglow of an atmospheric pressure Ar/O2 radiofrequency plasma has been investigated experimentally. Spatially resolved mass spectrometry and laser induced fluorescence on OH radicals were used to estimate the intrusion of air in between the plasma torch and the substrate as a function of the torch-to-substrate separation distance. No air is detected, within the limits of measurement uncertainties, for separation distances smaller than 5 mm. For larger distances, the effect of ambient air can no longer be neglected, and radial gradients in the concentrations of species appear. The Ar 4p population, determined through absolute optical emission spectroscopy, is seen to decrease with separation distance, whereas a rise in emission from the N2(C--B) system is measured. The observed decay in Ar 4p and N2(C) populations for separation distances greater than 9mm is partly assigned to the increasing collisional quenching rate by N2 and O2 molecules from the entrained air....

  4. Intrinsic-Density Functionals

    CERN Document Server

    Engel, J

    2006-01-01

    The Hohenberg-Kohn theorem and Kohn-Sham procedure are extended to functionals of the localized intrinsic density of a self-bound system such as a nucleus. After defining the intrinsic-density functional, we modify the usual Kohn-Sham procedure slightly to evaluate the mean-field approximation to the functional, and carefully describe the construction of the leading corrections for a system of fermions in one dimension with a spin-degeneracy equal to the number of particles N. Despite the fact that the corrections are complicated and nonlocal, we are able to construct a local Skyrme-like intrinsic-density functional that, while different from the exact functional, shares with it a minimum value equal to the exact ground-state energy at the exact ground-state intrinsic density, to next-to-leading order in 1/N. We briefly discuss implications for real Skyrme functionals.

  5. Synthesis of Long Afterglow Phosphor CaAl2Si2O8:Eu2+, Dy3+ via Sol-Gel Technique and Its Optical Properties

    Institute of Scientific and Technical Information of China (English)

    Wang Yinhai; Wang Zhiyu; Zhang Pengyue; Zhang Fuan; Fan Xianping; Qian Guodong

    2005-01-01

    The long afterglow phosphor CaAl2Si2O8:Eu2+, Dy3+ was prepared by a sol-gel method. The sol-gel process and the structure of the phosphor were investigated by means of X-ray diffraction analysis (XRD). It is found that the single anorthite phase formed at about 1000 ℃, which is 300 ℃ lower than that required for the conventional solid state reaction. The obtained phosphor powders are easier to grind than those of solid state method and the partical size of phosphor has a relative narrow distribution of 200 to 500 nm. The photoluminescence and afterglow properties of the phosphor were also characterized. An obvious blue shift occurs in the excitation and emission spectra of phosphors obtained by sol-gel and solid state reaction methods. The change of the fluorescence spectra can be attributed to the sharp decrease of the crystalline grain size of the phosphor resulted from the sol-gel technique.

  6. High energy emission of GRB 130427A: evidence for inverse Compton radiation

    CERN Document Server

    Fan, Yi-Zhong; Zhang, Fu-Wen; Liang, Yun-Feng; He, Hao-Ning; Zhou, Bei; Yang, Rui-Zhi; Jin, Zhi-Ping; Wei, Da-Ming

    2013-01-01

    A nearby super-luminous burst GRB 130427A was simultaneously detected by five $\\gamma$-ray space telescopes ({\\it Swift}, Fermi-GBM/LAT, Konus-Wind, SPI-ACS/INTEGRAL and AGILE) and by three RAPTOR full-sky persistent monitors. The isotropic $\\gamma-$ray energy release is of $\\sim 10^{54}$ erg and the absence of a jet break in the X-ray afterglow lightcurve up to $t>7$ days suggests an intrinsic energy release of $> 10^{52}$ erg, rendering it the most powerful explosion among the GRBs with a redshift $z\\leq 0.5$. The emission above 100 MeV lasted about one day and four photons are at energies greater than 40 GeV. We show that the count rate of 100 MeV-100 GeV emission may be mainly accounted for by the forward shock synchrotron radiation and the inverse Compton radiation likely dominates at GeV-TeV energies. In particular, an inverse Compton radiation origin is established for the $\\sim (95.3,~47.3,~41.4)$ GeV photons arriving at $t\\sim (243,~256.3,~610.6)$ s after the trigger of Fermi-GBM. Interestingly, the ...

  7. Curvature Effect and the Spectral Softening Phenomenon Detected in GRB Afterglows

    Indian Academy of Sciences (India)

    Y.-P. Qin

    2011-03-01

    Detection of radiation from a relativistic fireball would be affected by the so-called curvature effect. I illustrate the expected temporal and spectral behaviours of this effect and show that it can well explain the observed spectral softening in the early GRB afterglows.

  8. The afterglow and complex environment of the optically dim burst GRB 980613

    DEFF Research Database (Denmark)

    Hjorth, J.; Thomsen, Bente; Nielsen, S.R.

    2002-01-01

    of the optical afterglow was mainly due to the fairly at spectral shape rather than internal reddening in the host galaxy. We also present late-time Hubble Space Telescope/Space Telescope Imaging Spectrograph images of the field in which GRB 980613 occurred, obtained 799 days after the burst. These images show...

  9. The extraordinarily bright optical afterglow of GRB 991208 and its host galaxy

    DEFF Research Database (Denmark)

    Castro-Tirado, A.J.; Sokolov, V.V.; Gorosabel, J.

    2001-01-01

    days. which is very likely due to the jet effect. and it is followed by a much steeper decay with constant -3.2 +/- 0.2. the fastest one ever seen in a GRB optical afterglow. A negative detection in several all-sky films taken simultaneously with the er ent. that otherwise would have reached naked eye...

  10. Investigation of the strategies for targeting of the afterglow nanoparticles to tumor cells.

    Science.gov (United States)

    Rashidi, Leila Hossein; Homayoni, Homa; Zou, Xiaoju; Liu, Li; Chen, Wei

    2016-03-01

    Afterglow nanoparticles have been widely investigated as new agents for cancer imaging and as a light source for photodynamic activation for cancer treatment. For both applications, the targeting of the afterglow nanoparticles to tumor cells is an important and challenging issue. Here we report the strategies for targeting Sr3MgSi2O8:Eu(2+),Dy(3+) afterglow nanoparticles to tumor cells by conjugating with variety of targeting molecules such as folic acid, RGD peptide, and R-11 peptide. For folic acid targeting, experimental observations were conducted on PC-3 cells (folate receptor negative), MCF-7 (folate receptor positive), and KB cells (folate receptor positive) to compare the cellular uptake and confirm targeted delivery. For the cyclic RGDfK peptide, experiments were carried out on the integrin αvβ3 positive MDA-MB-231 breast cancer cell line and the integrin αvβ3 negative MCF-7 breast cancer cell lines in order to compare the cellular uptakes. As for R11-SH peptide, cellular uptake of the afterglow nanoparticles was observed on LNCaP and PC3 prostate cancer cell lines. All the observations showed that the cellular uptakes of the nanoparticles were enhanced by conjugation to variety of targeting molecules which are specific for breast and prostate cancer cells.

  11. Practical flux prescriptions for gamma-ray burst afterglows, from early to late times

    NARCIS (Netherlands)

    Leventis, K.; van Eerten, H.J.; Meliani, Z.; Wijers, R.A.M.J.

    2012-01-01

    We present analytic flux prescriptions for broad-band spectra of self-absorbed and optically thin synchrotron radiation from gamma-ray burst afterglows, based on 1D relativistic hydrodynamic simulations. By treating the evolution of critical spectrum parameters as a power-law break between the ultra

  12. Analysing afterglows using integral field spectroscopy: GRB 060605, the first practical example

    CERN Document Server

    Ferrero, Patrizia; Kann, David Alexander; Savaglio, Sandra; Palazzi, Eliana; Maiorano, Elisabetta; Böhm, Petra; Schulze, Steve; Grupe, Dirk; Oates, Samantha R; Sánchez, Sebastián F; Amati, Lorenzo; Greiner, Jochen; Hjorth, Jens; Malesani, Daniele; Barthelmy, Scott D; Gorosabel, Javier; Masetti, Nicola; Roth, Martin M

    2008-01-01

    GRB 060605 was a long and relatively faint gamma-ray burst detected by \\emph{Swift}/BAT with a duration of about 20 sec. Its afterglow could be observed with \\emph{Swift}/XRT for nearly 1 day while \\emph{Swift}/UVOT could detect the afterglow during the first 6 hours after the event. Here, we report on integral field spectroscopy of its afterglow performed with PMAS/PPak mounted at the Calar Alto 3.5 m telescope. In addition, we report on a detailed analysis of XRT and UVOT data and on the results of deep late-time VLT observations, which reveal the GRB host galaxy. We find that the burst occured at a redshift of $z$=3.773, possibly associated with a faint, $R_C=26.4 \\pm 0.3$ host. Based on the optical and X-ray data we deduce information on the SED of the afterglow, the position of the cooling frequency in the SED, the nature of the circumburst environment, its collimation factor, and its energetics. We find that the GRB fireball was expanding into a constant-density medium and that the explosion was collima...

  13. GRB 110530A: Peculiar Broad Bump and Delayed Plateau in Early Optical Afterglows

    Science.gov (United States)

    Zhong, Shu-Qing; Xin, Li-Ping; Liang, En-Wei; Wei, Jian-Yan; Urata, Yuji; Huang, Kui-Yun; Qiu, Yu-Lei; Deng, Can-Min; Wang, Yuan-Zhu; Deng, Jin-Song

    2016-11-01

    We report our very early optical observations of GRB 110530A and investigate its jet properties together with its X-ray afterglow data. A peculiar broad onset bump followed by a plateau is observed in its early R band afterglow light curve. The optical data in the other bands and the X-ray data are well consistent with the temporal feature of the R band light curve. Our joint spectral fits of the optical and X-ray data show that they are in the same regime, with a photon index of ∼1.70. The optical and X-ray afterglow light curves are well fitted with the standard external shock model by considering a delayed energy injection component. Based on our modeling results, we find that the radiative efficiency of the gamma-ray burst jet is ∼ 1 % and the magnetization parameter of the afterglow jet is \\lt 0.04 with a derived extremely low {ε }B (the ratio of shock energy to the magnetic field) of (1.64+/- 0.25)× {10}-6. These results indicate that the jet may be matter dominated. A discussion on delayed energy injection from the accretion of the late fall-back material of its pre-supernova star is also presented.

  14. VLT/X-shooter spectroscopy of the GRB 090926A afterglow

    NARCIS (Netherlands)

    D'Elia, V.; Fynbo, J.P.U.; Covino, S.; Goldoni, P.; Jakobsson, P.; Matteucci, F.; Piranomonte, S.; Sollerman, J.; Thöne, C.C.; Vergani, S.D.; Vreeswijk, P.M.; Watson, D.J.; Wiersema, K.; Zafar, T.; de Ugarte Postigo, A.; Flores, H.; Hjorth, J.; Kaper, L.; Levan, A.J.; Malesani, D.; Milvang-Jensen, B.; Pian, E.; Tagliaferri, G.; Tanvir, N.R.

    2010-01-01

    Aims. The aim of this paper is to study the environment and intervening absorbers of the gamma-ray burst GRB090926A through analyzing optical spectra of its afterglow. Methods. We analyzed medium-resolution spectroscopic observations (R = 10 000, corresponding to 30 km s(-1), S/N = 15-30 and wavelen

  15. X-ray spectral components observed in the afterglow of GRB 130925A

    DEFF Research Database (Denmark)

    Bellm, Eric C.; Barrière, Nicolas M.; Bhalerao, Varun

    2014-01-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at >4σ significance, and its spectral shape varies between...

  16. VLT/X-shooter spectroscopy of the GRB 120327A afterglow

    DEFF Research Database (Denmark)

    D'Elia, V.; Fynbo, Johan Peter Uldall; Goldoni, P.;

    2014-01-01

    We present a study of the environment of the Swift long gamma-ray burst GRB 120327A at z ~2.8 through optical spectroscopy of its afterglow. We analyzed medium-resolution, multi-epoch spectroscopic observations (~7000 - 12000, corresponding to ~ 15 - 23 km/s, S/N = 15- 30 and wavelength range 3000...

  17. The afterglow and complex environment of the optically dim burst GRB 980613

    DEFF Research Database (Denmark)

    Hjorth, J.; Thomsen, Bente; Nielsen, S.R.;

    2002-01-01

    of the optical afterglow was mainly due to the fairly at spectral shape rather than internal reddening in the host galaxy. We also present late-time Hubble Space Telescope/Space Telescope Imaging Spectrograph images of the field in which GRB 980613 occurred, obtained 799 days after the burst. These images show...

  18. The properties of the 2175AA extinction feature discovered in GRB afterglows

    CERN Document Server

    Zafar, Tayyaba; Eliasdottir, Ardis; Fynbo, Johan P U; Kruhler, Thomas; Schady, Patricia; Leloudas, Giorgos; Jakobsson, Pall; Thone, Christina C; Perley, Daniel A; Morgan, Adam N; Bloom, Joshua; Greiner, Jochen

    2012-01-01

    The unequivocal, spectroscopic detection of the 2175 bump in extinction curves outside the Local Group is rare. To date, the properties of the bump have been examined in only two GRB afterglows (GRB 070802 and GRB 080607). In this work we analyse in detail the detections of the 2175 extinction bump in the optical spectra of the two further GRB afterglows: GRB 080605 and 080805. We gather all available optical/NIR photometric, spectroscopic and X-ray data to construct multi-epoch SEDs for both GRB afterglows. We fit the SEDs with the Fitzpatrick & Massa (1990) model with a single or broken PL. We also fit a sample of 38 GRB afterglows, known to prefer a SMC-type extinction curve, with the same model. We find that the SEDs of GRB 080605 and GRB 080805 at two epochs are fit well with a single PL with a derived extinction of A_V = 0.52(+0.13 -0.16) and 0.50 (+0.13 -0.10), and 2.1(+0.7-0.6) and 1.5+/-0.2 respectively. While the slope of the extinction curve of GRB 080805 is not well-constrained, the extinction...

  19. Dust extinction in high-z galaxies with gamma-ray burst afterglow spectroscopy

    DEFF Research Database (Denmark)

    Elíasdóttir, Á.; Fynbo, J. P. U.; Hjorth, J.

    2009-01-01

    We report the clear detection of the 2175 Å dust absorption feature in the optical afterglow spectrum of the gamma-ray burst (GRB) GRB 070802 at a redshift of z = 2.45. This is the highest redshift for a detected 2175 Å dust bump to date, and it is the first clear detection of the 2175 Å bump in ...

  20. POLARIZATION EVOLUTION OF EARLY OPTICAL AFTERGLOWS OF GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Mi-Xiang; Dai, Zi-Gao [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wu, Xue-Feng, E-mail: dzg@nju.edu.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-01-10

    The central engine and jet composition of gamma-ray bursts (GRBs) remain mysterious. Here we suggest that observations on the polarization evolution of early optical afterglows may shed light on these questions. We first study the dynamics of a reverse shock and a forward shock that are generated during the interaction of a relativistic jet and its ambient medium. The jet is likely magnetized with a globally large-scale magnetic field from the central engine. The existence of the reverse shock requires that the magnetization degree of the jet should not be high (σ ≤ 1), so that the jet is mainly composed of baryons and leptons. We then calculate the light curves and polarization evolution of early optical afterglows and find that when the polarization position angle changes by 90° during the early afterglow, the polarization degree is zero for a toroidal magnetic field but is very likely to be nonzero for an aligned magnetic field. This result would be expected to provide a probe for the central engine of GRBs because an aligned field configuration could originate from a magnetar central engine and a toroidal field configuration could be produced from a black hole via the Blandford–Znajek mechanism. Finally, for such two kinds of magnetic field configurations, we fit the observed data of the early optical afterglow of GRB 120308A equally well.

  1. Testing Models for the Shallow Decay Phase of Gamma-Ray Burst Afterglows with Polarization Observations

    CERN Document Server

    Lan, Mi-Xiang; Dai, Zi-Gao

    2016-01-01

    The X-ray afterglows of almost one half of gamma-ray bursts (GRBs) have been discovered to have a shallow decay phase by the {\\em Swift} satellite, whose origin remains mysterious. Two main models have been proposed to explain this phase, relativistic wind bubbles (RWBs) and structured ejecta, which could originate from millisecond magnetars and rapidly-rotating black holes, respectively. Based on these models, we here investigate polarization evolution in the shallow decay phase of X-ray and optical afterglows. We find that in the RWB model, a significant bump of the polarization degree evolution curve appears during the shallow decay phase of both optical and X-ray afterglows, while the polarization position angle changes its direction by $90^\\circ$ abruptly. In the structured ejecta model, however, the polarization degree does not evolve significantly during the shallow decay phase of afterglows, no matter whether the magnetic field configuration in the ejecta is random or globally large-scale. Therefore, ...

  2. Effect of Eu{sup 2+} concentration on afterglow suppression in CsI:Tl, Eu

    Energy Technology Data Exchange (ETDEWEB)

    Kappers, L.A. [Department of Physics, University of Connecticut, Storrs, CT 06269-3046 (United States)], E-mail: lawrence.kappers@uconn.edu; Bartram, R.H.; Hamilton, D.S. [Department of Physics, University of Connecticut, Storrs, CT 06269-3046 (United States); Brecher, C.; Lempicki, A. [ALEM Associates, 303A Commonwealth Avenue, Boston, MA 02115 (United States); Gaysinskiy, V.; Ovechkina, E.E.; Nagarkar, V.V. [Radiation Monitoring Devices, Inc., 44 Hunt str., Watertown, MA 02472 (United States)

    2007-04-15

    Combined radioluminescence and thermoluminescence experiments on the co-doped scintillator material CsI:Tl, Eu were extended in the present investigation to a sample with diminished europium concentration. Simulations based on postulated rate equations with empirically adjusted parameters are consistent with observed insensitivity of afterglow suppression to europium concentration for sufficiently short radiation times.

  3. BRIGHT BROADBAND AFTERGLOWS OF GRAVITATIONAL WAVE BURSTS FROM MERGERS OF BINARY NEUTRON STARS

    Energy Technology Data Exchange (ETDEWEB)

    Gao He; Ding Xuan; Wu Xuefeng [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Zhang Bing [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States); Dai Zigao, E-mail: xfwu@pmo.ac.cn, E-mail: zhang@physics.unlv.edu, E-mail: dzg@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2013-07-10

    If double neutron star mergers leave behind a massive magnetar rather than a black hole, then a bright early afterglow can follow the gravitational wave burst (GWB) even if there is no short gamma-ray burst (SGRB)-GWB association or if there is an association but the SGRB does not beam toward Earth. Besides directly dissipating the proto-magnetar wind, as suggested by Zhang, here we suggest that the magnetar wind could push the ejecta launched during the merger process and, under certain conditions, would reach a relativistic speed. Such a magnetar-powered ejecta, when interacting with the ambient medium, would develop a bright broadband afterglow due to synchrotron radiation. We study this physical scenario in detail and present the predicted X-ray, optical, and radio light curves for a range of magnetar and ejecta parameters. We show that the X-ray and optical light curves usually peak around the magnetar spin-down timescale ({approx}10{sup 3}-10{sup 5} s), reaching brightnesses readily detectable by wide-field X-ray and optical telescopes, and remain detectable for an extended period. The radio afterglow peaks later, but is much brighter than the case without a magnetar energy injection. Therefore, such bright broadband afterglows, if detected and combined with GWBs in the future, would be a probe of massive millisecond magnetars and stiff equations of state for nuclear matter.

  4. GRB 110530A: Peculiar Broad Bump and Delayed Plateau in Early Optical Afterglows

    CERN Document Server

    Zhong, Shu-Qing; Liang, En-Wei; Wei, Jian-Yan; Urata, Yuji; Huang, Kui-Yun; Qiu, Yu-Lei; Deng, Can-Min; Wang, Yuan-Zhu; Deng, Jin-Song

    2016-01-01

    We report our very early optical observations of GRB 110530A and investigate its jet properties together with its X-ray afterglow data. A peculiar broad onset bump followed by a plateau is observed in its early R band afterglow lightcurve. The optical data in the other bands and the X-ray data are well consistent with the temporal feature of the R band lightcurve. Our joint spectral fits of the optical and X-ray data show that they are in the same regime, with a photon index of $\\sim 1.70$. The optical and X-ray afterglow lightcurves are well fitted with the standard external shock model by considering a delayed energy injection component. Based on our modeling results, we find that the radiative efficiency of the GRB jet is $\\sim 1\\%$ and the magnetization parameter of the afterglow jet is $<0.04$ with the derived extremely low $\\epsilon_B$ (the fraction of shock energy to magnetic field) of $(1.64\\pm 0.25)\\times 10^{-6}$. These results indicate that the jet may be matter dominated. Discussion on delayed ...

  5. Cosmic Gamma-Ray Bursts, Their Afterglows, and Their Host Galaxies

    CERN Document Server

    Hurley, K; Djorgovski, S G

    2002-01-01

    This is a review article for the book "Compact Stellar X-Ray Sources", Editors W. Lewin and M. van der Klis, to be published by Cambridge University Press in 2003. It covers the phenomenology of cosmic gamma-ray bursts, the theory of their afterglows, and the observations and interpretation of their host galaxies.

  6. Implications of the Early X-Ray Afterglow Light Curves of Swift GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Granot, Jonathan; /KIPAC, Menlo Park; Konigl, Arieh; /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI; Piran, Tsvi; /Hebrew U.

    2006-01-17

    According to current models, gamma-ray bursts (GRBs) are produced when the energy carried by a relativistic outflow is dissipated and converted into radiation. The efficiency of this process, {epsilon}{sub {gamma}}, is one of the critical factors in any GRB model. The X-ray afterglow light curves of Swift GRBs show an early stage of flattish decay. This has been interpreted as reflecting energy injection. When combined with previous estimates, which have concluded that the kinetic energy of the late ({approx}> 10 hr) afterglow is comparable to the energy emitted in {gamma}-rays, this interpretation implies very high values of {epsilon}{sub {gamma}}, corresponding to {approx}> 90% of the initial energy being converted into {gamma}-rays. Such a high efficiency is hard to reconcile with most models, including in particular the popular internal-shocks model. We re-analyze the derivation of the kinetic energy from the afterglow X-ray flux and re-examine the resulting estimates of the efficiency. We confirm that, if the flattish decay arises from energy injection and the pre-Swift broad-band estimates of the kinetic energy are correct, then {epsilon}{sub {gamma}} {approx}> 0.9. We discuss various issues related to this result, including an alternative interpretation of the light curve in terms of a two-component outflow model, which we apply to the X-ray observations of GRB 050315. We point out, however, that another interpretation of the flattish decay--a variable X-ray afterglow efficiency (e.g., due to a time dependence of afterglow shock microphysical parameters)--is possible. We also show that direct estimates of the kinetic energy from the late X-ray afterglow flux are sensitive to the assumed values of the shock microphysical parameters and suggest that broad-band afterglow fits might have underestimated the kinetic energy (e.g., by overestimating the fraction of electrons that are accelerated to relativistic energies). Either one of these possibilities implies a

  7. Lorentz invariant intrinsic decoherence

    CERN Document Server

    Milburn, G J

    2003-01-01

    Quantum decoherence can arise due to classical fluctuations in the parameters which define the dynamics of the system. In this case decoherence, and complementary noise, is manifest when data from repeated measurement trials are combined. Recently a number of authors have suggested that fluctuations in the space-time metric arising from quantum gravity effects would correspond to a source of intrinsic noise, which would necessarily be accompanied by intrinsic decoherence. This work extends a previous heuristic modification of Schr\\"{o}dinger dynamics based on discrete time intervals with an intrinsic uncertainty. The extension uses unital semigroup representations of space and time translations rather than the more usual unitary representation, and does the least violence to physically important invariance principles. Physical consequences include a modification of the uncertainty principle and a modification of field dispersion relations, in a way consistent with other modifications suggested by quantum grav...

  8. Intrinsic Time Quantum Geometrodynamics

    CERN Document Server

    Ita, Eyo Eyo; Yu, Hoi-Lai

    2015-01-01

    Quantum Geometrodynamics with intrinsic time development and momentric variables is presented. An underlying SU(3) group structure at each spatial point regulates the theory. The intrinsic time behavior of the theory is analyzed, together with its ground state and primordial quantum fluctuations. Cotton-York potential dominates at early times when the universe was small; the ground state naturally resolves Penrose's Weyl Curvature Hypothesis, and thermodynamic and gravitational `arrows of time' point in the same direction. Ricci scalar potential corresponding to Einstein's General Relativity emerges as a zero-point energy contribution. A new set of fundamental canonical commutation relations without Planck's constant emerges from the unification of Gravitation and Quantum Mechanics.

  9. Intrinsic contractures of the hand.

    Science.gov (United States)

    Paksima, Nader; Besh, Basil R

    2012-02-01

    Contractures of the intrinsic muscles of the fingers disrupt the delicate and complex balance of intrinsic and extrinsic muscles, which allows the hand to be so versatile and functional. The loss of muscle function primarily affects the interphalangeal joints but also may affect etacarpophalangeal joints. The resulting clinical picture is often termed, intrinsic contracture or intrinsic-plus hand. Disruption of the balance between intrinsic and extrinsic muscles has many causes and may be secondary to changes within the intrinsic musculature or the tendon unit. This article reviews diagnosis, etiology, and treatment algorithms in the management of intrinsic contractures of the fingers. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. Separating weak lensing and intrinsic alignments using radio observations

    CERN Document Server

    Whittaker, Lee; Battye, Richard A

    2015-01-01

    We discuss methods for performing weak lensing using radio observations to recover information about the intrinsic structural properties of the source galaxies. Radio surveys provide unique information that can benefit weak lensing studies, such as HI emission, which may be used to construct galaxy velocity maps, and polarized synchrotron radiation; both of which provide information about the unlensed galaxy and can be used to reduce galaxy shape noise and the contribution of intrinsic alignments. Using a proxy for the intrinsic position angle of an observed galaxy, we develop techniques for cleanly separating weak gravitational lensing signals from intrinsic alignment contamination in forthcoming radio surveys. Random errors on the intrinsic orientation estimates introduce biases into the shear and intrinsic alignment estimates. However, we show that these biases can be corrected for if the error distribution is accurately known. We demonstrate our methods using simulations, where we reconstruct the shear an...

  11. Predicting Intrinsic Motivation

    Science.gov (United States)

    Martens, Rob; Kirschner, Paul A.

    2004-01-01

    Intrinsic motivation can be predicted from participants' perceptions of the social environment and the task environment (Ryan & Deci, 2000)in terms of control, relatedness and competence. To determine the degree of independence of these factors 251 students in higher vocational education (physiotherapy and hotel management) indicated the extent to…

  12. A study of gamma ray bursts with afterglow plateau phases associated with supernovae

    Science.gov (United States)

    Dainotti, M. G.; Nagataki, S.; Maeda, K.; Postnikov, S.; Pian, E.

    2017-04-01

    Context. The analysis of 176 gamma ray burst (GRB) afterglow plateaus observed by Swift from GRBs with known redshifts revealed that the subsample of long GRBs associated with supernovae (LONG-SNe), comprising 19 events, presents a very high correlation coefficient between the luminosity at the end of the plateau phase LX(Ta) = La and the end time of the plateau . Furthermore, these SNe Ib/c associated with GRBs also obey the peak-magnitude stretch relation, which is similar to that used to standardize the SNe Ia. Aims: Our aim is to investigate a category of GRBs with plateau and associated with SNe to compare our correlation for this sample with the correlation for long GRBs for which no associated SN has been observed (hereafter LONG-NO-SNe, 128 GRBs) and to check whether there is a difference among these subsamples. Methods: We first adopted a nonparametric statistical method to take redshift evolution into account and to check if and how this effect may steepen the slope for the LONG-NO-SNe sample. This procedure is necessary because this sample is observed at much higher redshift than the GRB-SNe sample. Therefore, removing selection bias is the first step before any comparison among samples observed at different redshifts could be properly performed. Then, we applied the T-student test to evaluate a statistical difference between the slopes of the two samples. Results: We demonstrate that there is no evolution for the slope of the LONG-NO-SNe sample and no evolution is expected for GRBs observed at small redshifts such as those present in the LONG-SNe sample. The difference between the slope of the LONG-NO-SNe and the slope of LONG-SNe, i.e., those with firm spectral detection of SN components, is statistically significant (P = 0.005). Conclusions: This possibly suggests that, unlike LONG-NO-SNe, LONG-SNe with firm spectroscopic features of the associated SNe might not require a standard energy reservoir in the plateau phase. Therefore, this analysis may

  13. Two types of softening detected in X-ray afterglows of Swift bursts: internal and external shock origins?

    CERN Document Server

    Qin, Y -P; Fan, J H; Lu, R -J

    2008-01-01

    The softening process observed in the steep decay phase of early X-ray afterglows of Swift bursts has remained a puzzle since its discovery. The softening process can also be observed in the later phase of the bursts and its cause has also been unknown. Recently, it was suggested that, influenced by the curvature effect, emission from high latitudes would shift the Band function spectrum from higher energy band to lower band, and this would give rise to the observed softening process accompanied by a steep decay of the flux density. The curvature effect scenario predicts that the terminating time of the softening process would be correlated with the duration of the process. In this paper, based on the data from the UNLV GRB group web-site, we found an obvious correlation between the two quantities. In addition, we found that the softening process can be divided into two classes: the early type softening ($t_{s,max}\\leq "4000"s$) and the late type softening ($t_{s,max} > "4000"s$). The two types of softening s...

  14. The Afterglow and Early-Type Host Galaxy of the Short GRB 150101B at z=0.1343

    CERN Document Server

    Fong, Wen-fai; Chornock, Ryan; Berger, Edo; Shappee, Benjamin J; Levan, Andrew J; Tanvir, Nial R; Smith, Nathan; Milne, Peter A; Laskar, Tanmoy; Fox, Derek B; Lunnan, Ragnhild; Blanchard, Peter K; Hjorth, Jens; Wiersema, Klaas; van der Horst, Alexander J; Zaritsky, Dennis

    2016-01-01

    We present the discovery of the X-ray and optical afterglows of the short-duration GRB 150101B, pinpointing the event to an early-type host galaxy at z=0.1343 +/- 0.0030. This makes GRB 150101B the most nearby short GRB with an early-type host galaxy discovered to date. Fitting the spectral energy distribution of the host galaxy results in an inferred stellar mass of ~7x10^10 M_sol, stellar population age of ~2-2.5 Gyr, and star formation rate of 9 deg. Using observations extending to ~30 days, we place upper limits of <(2-4)x10^41 erg s^-1 on associated kilonova emission. We compare searches following previous short GRBs to existing kilonova models, and demonstrate the difficulty of performing effective kilonova searches from cosmological short GRBs using current ground-based facilities. We show that at the Advanced LIGO/VIRGO horizon distance of 200 Mpc, searches reaching depths of ~23-24 AB mag are necessary to probe a meaningful range of kilonova models.

  15. On the difficulty of N({sup 4}S) atom recombination to explain the appearance of the pink afterglow in a N{sub 2} flowing discharge

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, J [Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal); Sa, P A [Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal); Departamento de Fisica, Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto (Portugal); Guerra, V [Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal)

    2006-01-07

    The possibility that the pink afterglow (PA) of a flowing nitrogen discharge occurs as a result of recombination of N({sup 4}S) atoms is evaluated and discussed, based on a detailed kinetic model for a microwave discharge and post-discharge. The present simulation shows that the N{sub 2}{sup +}(B{sup 2}{sigma}{sub u}{sup +},v) states responsible for the emission of the PA cannot be created via an indirect mechanism initiated with atomic recombination. Alternatively, it is indicated that the PA may have its origin in non-resonant vibration-vibration energy-exchange processes between N{sub 2}(X{sup 1}{sigma}{sub g}{sup +},v) molecules, which lead to an overpopulation of high levels of the vibrational manifold.

  16. Quantifying the Sexual Afterglow: The Lingering Benefits of Sex and Their Implications for Pair-Bonded Relationships.

    Science.gov (United States)

    Meltzer, Andrea L; Makhanova, Anastasia; Hicks, Lindsey L; French, Juliana E; McNulty, James K; Bradbury, Thomas N

    2017-05-01

    Sex presumably facilitates pair bonding, but how do partners remain pair-bonded between sexual acts? Evolutionary perspectives suggest that sexual afterglow serves this purpose. We explored how long sexual satisfaction would remain elevated following sex and predicted that stronger sexual afterglow would characterize more satisfying partnerships. We pooled the data from two independent, longitudinal studies of newlywed couples to examine these issues. Spouses reported their daily sexual activity and sexual satisfaction for 14 days and their marital satisfaction at baseline and 4 or 6 months later. Results demonstrated that sexual satisfaction remained elevated approximately 48 hr after sex, and spouses experiencing a stronger afterglow reported higher levels of marital satisfaction both at baseline and over time. We interpret these findings as evidence that sexual afterglow is a proximal cognitive mechanism through which sex promotes pair bonding.

  17. Blue–green afterglow of BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Bao-gai [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); Ma, Qing-lan [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); School of Electronics and Information, Nantong University, Jiangsu 226019 (China); Xiong, Rui [School of Physics and Technology, Wuhan University, Hubei 430072 (China); Li, Xiazhang [Analysis and Testing Center, Changzhou University, Jiangsu 213164 (China); Huang, Yuan Ming, E-mail: dongshanisland@126.com [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China)

    2016-03-15

    Highlights: • Afterglow can be achieved when Eu{sup 2+} is absent in the DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. • The afterglow of DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors is discernible to naked eyes for minutes. • Dy{sup 3+} introduced trap centers are believed to be responsible for the afterglow. - Abstract: Dy{sup 3+} doped barium aluminate (BaAl{sub 2}O{sub 4}:Dy{sup 3+}) phosphors were prepared via the sol–gel combustion route at the ignition temperature of 600 °C. The phosphors were characterized with X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Regardless of the absence of Eu{sup 2+} luminescent centers, broadband blue–green afterglow with its peak at about 490 nm was recorded in the BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. The decay profile of the blue–green afterglow can be best fitted into a two-component exponential function with the two lifetime decay constants to be 8.81 and 45.25 s, respectively. The observation of blue–green afterglow from BaAl{sub 2}O{sub 4}:Dy{sup 3+} in the absence of Eu{sup 2+} provides unique opportunity in unveiling the afterglow mechanisms of rare-earth doped alkaline-metal aluminates. Possible mechanisms on the blue–green afterglow in BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors are discussed in terms of the Dy{sup 3+} ions introduced trap centers as well as luminescent centers in the crystal lattice.

  18. Hubble Space Telescope Observations of the Afterglow, Supernova and Host Galaxy Associated with the Extremely Bright GRB 130427A

    Science.gov (United States)

    Levan, A.J.; Tanvir, N. R.; Fruchter, A. S.; Hjorth, J.; Pian, E.; Mazzali, P.; Hounsell, R. A.; Perley, D. A.; Cano, Z.; Graham, J.; hide

    2014-01-01

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst, GRB 130427A. At z=0.34 this burst affords an excellent opportunity to study the supernova and host galaxy associated with an intrinsically extremely luminous burst (E(sub iso) greater than 10(exp 54) erg): more luminous than any previous GRB with a spectroscopically associated supernova. We use the combination of the image quality, UV capability and and invariant PSF of HST to provide the best possible separation of the afterglow, host and supernova contributions to the observed light approximately 17 rest-frame days after the burst utilising a host subtraction spectrum obtained 1 year later. Advanced Camera for Surveys (ACS) grism observations show that the associated supernova, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, vph approximately 15,000 kilometers per second). The positions of the bluer features are better matched by the higher velocity SN 2010bh (vph approximately 30,000 kilometers per second), but SN 2010bh (vph approximately 30,000 kilometers per second but this SN is significantly fainter, and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated approximately 4 kpc from the nucleus of a moderately star forming (1 Solar Mass yr(exp-1)), possibly interacting disc galaxy. The absolute magnitude, physical size and morphology of this galaxy, as well as the location of the GRB within it are also strikingly similar to those of GRB980425SN 1998bw. The similarity of supernovae and environment from both the most luminous and least luminous GRBs suggests broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  19. Hubble space telescope observations of the afterglow, supernova, and host galaxy associated with the extremely bright GRB 130427A

    Energy Technology Data Exchange (ETDEWEB)

    Levan, A. J. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Tanvir, N. R.; Wiersema, K. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); Fruchter, A. S.; Hounsell, R. A.; Graham, J. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Hjorth, J.; Fynbo, J. P. U. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Pian, E. [INAF, Trieste Astronomical Observatory, via G.B. Tiepolo 11, I-34143 Trieste (Italy); Mazzali, P. [Astrophysics Research Institute, Liverpool John Moores University, IC2 Liverpool Science Park 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Perley, D. A. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd., Pasadena, CA 91125 (United States); Cano, Z. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Kouveliotou, C. [Science and Technology Office, ZP12, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Pe' er, A. [Department of Physics, University College Cork, Cork (Ireland); Misra, K., E-mail: a.j.levan@warwick.ac.uk [Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital-263 002 (India)

    2014-09-10

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst (GRB), GRB 130427A. At z = 0.34, this burst affords an excellent opportunity to study the supernova (SN) and host galaxy associated with an intrinsically extremely luminous burst (E {sub iso} > 10{sup 54} erg): more luminous than any previous GRB with a spectroscopically associated SN. We use the combination of the image quality, UV capability, and invariant point-spread function of HST to provide the best possible separation of the afterglow, host, and SN contributions to the observed light ∼17 rest-frame days after the burst, utilizing a host subtraction spectrum obtained one year later. Advanced Camera for Surveys grism observations show that the associated SN, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, v {sub ph} ∼ 15, 000 km s{sup –1}). The positions of the bluer features are better matched by the higher velocity SN 2010bh (v {sub ph} ∼ 30, 000 km s{sup –1}), but this SN is significantly fainter and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated ∼4 kpc from the nucleus of a moderately star forming (1 M {sub ☉} yr{sup –1}), possibly interacting disk galaxy. The absolute magnitude, physical size, and morphology of this galaxy, as well as the location of the GRB within it, are also strikingly similar to those of GRB 980425/SN 1998bw. The similarity of the SNe and environment from both the most luminous and least luminous GRBs suggests that broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  20. The Physics of Gamma-Ray Burst Afterglows and the Nature of Their Host Galaxies

    Science.gov (United States)

    Vreeswijk, Paul

    Gamma-ray bursts are brief flashes of γ-rays, discovered by the cold-war Vela satellites in the early 1970s. For over two decades the distance scale of these explosions was unknown. In the early 1990s, the Burst and Transient Source experiment onboard the Compton Gamma-Ray Observatory showed gamma-ray bursts to have an isotropic sky distribution, suggestive of a cosmological origin. Thanks to the discovery of X-ray and optical afterglows by BeppoSAX, their distant extra-galactic nature was definitely established in 1997. We discuss the history and current status of the study of gamma-ray burst afterglows, and future VLT observations that can significantly advance the field.

  1. Effect of a Biased Probe on the Afterglow Operation of an ECR4 Ion Source

    CERN Document Server

    Hill, C E; Wenander, F; Wolf, B H

    2000-01-01

    Various experiments have been performed on a 14.5 GHz ECR4 in order to improve the ion yield. The source runs in pulsed afterglow mode, and provides currents ~120 emA of Pb27+ to the CERN Heavy Ion Facility on an operational basis. In the search for higher beam intensities, the effects of a pulsed biased disk on axis at the injection side were investigated with different pulse timing and voltage settings. No proof for absolute higher intensities was seen for any of these modifications. However, the yield from a poorly tuned/low-performing source could be improved and the extracted pulse was less noisy with bias voltage applied. The fast response on the bias implies that increases/decreases are not due to ionisation processes. A good tune for high yield of high charge states during the afterglow coincides with a high plasma potential.

  2. Afterglow from GRB 070610/Swift J195509.6+261406:An explanation using the fireball model

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    GRB 070610,which is also named Swift J195509.6+261406,is a peculiar Galactic transient with significant variability on short timescales in both X-ray and optical light curves.One possible explanation is that GRB 070610/Swift J195509.6 + 261406 is a soft gamma-ray repeater(SGR) in our Galaxy.Here,we use the fireball model,which is usually recognized as the standard model of gamma-ray burst(GRB) afterglows,and the energy injection hypothesis to interpret the X-ray and optical afterglow light curves of GRB 070610/Swift J195509.6 + 261406.It is found that the model is generally consistent with observations.

  3. Diverse Features of the Multiwavelength Afterglows of Gamma-Ray Bursts: Natural or Special?

    Directory of Open Access Journals (Sweden)

    J. J. Geng

    2016-01-01

    Full Text Available The detection of optical rebrightenings and X-ray plateaus in the afterglows of gamma-ray bursts (GRBs challenges the generic external shock model. Recently, we have developed a numerical method to calculate the dynamics of the system consisting of a forward shock and a reverse shock. Here, we briefly review the applications of this method in the afterglow theory. By relating these diverse features to the central engines of GRBs, we find that the steep optical rebrightenings would be caused by the fall-back accretion of black holes, while the shallow optical rebrightenings are the consequence of the injection of the electron-positron-pair wind from the central magnetar. These studies provide useful ways to probe the characteristics of GRB central engines.

  4. Diverse Features of the Multi-wavelength Afterglows of Gamma-ray Bursts: Natural or Special?

    CERN Document Server

    Geng, J J

    2016-01-01

    The detection of optical re-brightenings and X-ray plateaus in the afterglows of gamma-ray bursts (GRBs) challenges the generic external shock model. Recently, we have developed a numerical method to calculate the dynamic of the system consisting of a forward shock and a reverse shock. Here, we briefly review the applications of this method in the afterglow theory. By relating these diverse features to the central engines of GRBs, we find that the steep optical re-brightenings would be caused by the fall-back accretion of black holes, while the shallow optical re-brightenings are the consequence of the injection of the electron-positron-pair wind from the central magnetar. These studies provide useful ways to probe the characteristics of GRB central engines.

  5. Optical Afterglow Observations of the Unusual Short-Duration Gamma-Ray Burst 040924

    CERN Document Server

    Huang, K Y; Filippenko, A V; Hu, J H; Ip, W H; Kuo, P H; Li, W; Lin, H C; Lin, Z Y; Makishima, K; Onda, K; Qiu, Y; Tamagawa, T

    2005-01-01

    The 1-m telescope at Lulin Observatory and the 0.76-m Katzman Automatic Imaging Telescope at Lick Observatory were used to observe the optical afterglow of the short-duration (1.2--1.5 s) gamma-ray burst (GRB) 040924. This object has a soft high-energy spectrum, thus making it an exceptional case, perhaps actually belonging to the short-duration tail of the long-duration GRBs. Our data, combined with other reported measurements, show that the early R-band light curve can be described by two power laws with index alpha = -0.7 (at t = 16-50 min) and alpha = -1.06 (at later times). The rather small difference in the spectral indices can be more easily explained by an afterglow model invoking a cooling break rather than a jet break.

  6. STATISTICAL PROPERTIES OF GRB AFTERGLOW PARAMETERS AS EVIDENCE OF COSMOLOGICAL EVOLUTION OF THEIR HOST GALAXIES

    Directory of Open Access Journals (Sweden)

    Gregory Beskin

    2014-08-01

    Full Text Available The results of a study of 43 peaked R-band light curves of optical counterparts of gamma-ray bursts with known redshifts are presented. The parameters of optical transients were calculated in the comoving frame, and then a search for pair correlations between them was conducted. A statistical analysis showed a strong correlation between the peak luminosity and the redshift both for pure afterglows and for events with residual gamma activity, which cannot be explained as an effect of observational selection.This suggests a cosmological evolution of the parameters of the local interstellar medium around the sources of the gamma-ray burst. In the models of forward and reverse shock waves, a relation between the density of the interstellar medium and the redshift was built for gamma-ray burst afterglows, leading to a power-law dependence of the star-formation rate at regions around GRBs on redshift with a slope of about 6.

  7. Hyperluminal Signatures in the Afterglows of Gamma-Ray Bursts 980425 and 030329

    CERN Document Server

    Dado, Shlomo; De Rújula, A

    2016-01-01

    The late-time high-resolution X-ray and radio observations of GRB980425/SN1998bw, the closest known gamma ray burst (GRB) associated with a supernova (SN) explosion, may have actually resolved the hyperluminal source that produced the GRB and its afterglow. Its hyperluminal speed ~350c is consistent with that expected in the cannonball (CB) model of GRBs. The observed superluminal expansion of the late-time radio image of GRB030329/SN2003dh, the GRB with the brightest and longest followed up radio afterglow to date, is also consistent with that expected in the CB model of GRBs and extrapolates to an apparent early-time hyperluminal expansion.

  8. Studies on Self-Luminous Material and Coating with Long Persistent Yellow-Green Afterglow

    Institute of Scientific and Technical Information of China (English)

    邱关明; 孙彦彬; 陈永杰; 张明

    2003-01-01

    The preparation, properties, expression and luminescent mechanism of self-luminous material (SrAl2O4∶Eu2+, Dy3+) were discussed. The long afterglow luminescent coating was prepared by adding proper luminescent powders SrAl2O4∶Eu2+, Dy3+ and other aids into styrene/acrylic emulsion. The best prescription of the coating was defined. The properties of luminescent coating were determined. The primary factors which affect the coating properties were discussed.

  9. R■D Base of Super-long Afterglow Phosphors Established in Linxi

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Shandong Fengda Liangyu Chemicals Co. Ltd wasestablished in the industrial park of Linxi Luozhuang Districtrecently. The company focuses on the application of rareearth materials, taking development of high value-addedsuper-long afterglow phosphor materials as the guide. It has aleading technology in the world. By absorbing visible lightfor 5 to 10 minutes, the luminescence of the phosphormaterial developed by the company can last 12 to 15 hoursafter light is switched off. When applied with plastics, dope,r...

  10. Is there a 1998bw-like supernova in the afterglow of gamma ray burst 010921?

    CERN Document Server

    Dado, S; De Rújula, Alvaro; Dado, Shlomo; Dar, Arnon; Rujula, Alvaro De

    2002-01-01

    We use the very simple and successful Cannonball Model (CB) of gamma ray bursts (GRBs) and their afterglows (AGs) to analyze the observations of the strongly extinct optical AG of GRB 010921 with ground-based telescopes at early times, and with the HST at later time. We show that GRB 010921 was indeed associated with a 1998bw-like supernova at the GRB's redshift.

  11. Metastable-metastable collisions in the Orsay polarized electron source by helium afterglow

    Science.gov (United States)

    Brissaud, I.

    1995-01-01

    At Orsay the current of polarized electrons produced by the optically pumped helium afterglow does not vary as the metastable density, but as the density squared. That shows that spurious electrons are mixed to the electrons emitted by chemi-ionization reaction of the polarized metastables with CO 2 gas. In this paper it is suggested that these spurious electrons are produced by metastable-metastable collisions. The contribution of these collisions to the electron current and polarization is evaluated.

  12. Study of the metastable helium spin polarization in an optically pumped afterglow

    Science.gov (United States)

    Essabaa, S.; Schearer, L. D.; Arianer, J.; Brissaud, I.; Humblot, H.; Zerhouni, O.

    1994-05-01

    A very efficient technique of optical pumping is applied in order to polarize 2 3S 1 metastable 4He atoms within an afterglow by means of a high power LNA laser. An almost complete atom polarization is achieved. This allows the production of an electron beam of appreciable intensity with high polarization well suited to perform a polarized electron source for linear cw accelerators.

  13. Limitation of the Polarization by Radiation Trapping in a Helium Afterglow Electron Source

    Science.gov (United States)

    Brissaud, I.; Jacquemin, C.

    1995-01-01

    A polarized electron source using an optically pumped helium afterglow was built at Orsay. Unfortunately the spin polarization decreases at high metastable densities. Calculations of the radiation trapping effects in a weak magnetic field are presented using the Anderson formalism. Comparison with experimental data leads to the conclusion that these trapping effects are one explanation of this polarization decrease. Effects of the main parameters are studied. Some deductions for a new design can be made.

  14. Extinction of Beamed Gamma-ray Burst Afterglows in a Dense Circumstellar Cloud

    Institute of Scientific and Technical Information of China (English)

    Shun-Lin Liang; Zi-Gao Dai; Yong-Feng Huang; Tan Lu

    2003-01-01

    Broadband afterglow observations provide a probe of the density structure of the circumburst medium. In the spreading jet model, prompt and intense X-ray/UV radiation from the reverse shock may destroy and clear the dust in the circumburst cloud out to about 30 pc within the initial solid angle of the jet. As the jet expands significantly, optical radiation from the high-latitude part of the jet may suffer extinction by dust outside the initial solid angle, while radiation from the part within the initial solid angle can be observed without extinction. In previous studies, it is usually assumed that the extinction is complete. We calculate the extinction effect by taking the optical depth into account. Our numerical results show that a break appears in the light curve of optical afterglow but it extends over a factor of ~ 80 in time rather than a factor of ~ 10 in time for the case of strong dust extinction and a factor of ~ 60 in time for the case without dust extinction. These results may provide a way to judge how large the number density of the circumburst cloud is. Finally, we carry out a detailed modeling for the afterglow of GRB 000926.Our model can provide a good fit to the multi-color observations of this event.

  15. Extremely Soft X-ray Flash as the indicator of off-axis orphan GRB afterglow

    CERN Document Server

    Urata, Yuji; Yamazaki, Ryo; Sakamoto, Takanori

    2015-01-01

    We verified the off-axis jet model of X-ray flashes (XRFs) and examined a discovery of off-axis orphan gamma-ray burst (GRBs) afterglows. The XRF sample was selected on the basis of the following three factors: (1) a constraint on the lower peak energy of the prompt spectrum $E^{src}_{obs}$, (2) redshift measurements, and (3) multi-color observations of an earlier (or brightening) phase. XRF020903 was the only sample selected basis of these criteria. A complete optical multi-color afterglow light curve of XRF020903 obtained from archived data and photometric results in literature showed an achromatic brightening around 0.7 days. An off-axis jet model with a large observing angle (0.21 rad, which is twice the jet opening half-angle, $\\theta_{jet}$) can naturally describe the achromatic brightening and the prompt X-ray spectral properties. This result indicates the existence of off-axis orphan GRB afterglow light curves. Events with a larger viewing angle ($>\\sim2\\theta_{jet}$) could be discovered using an 8-m ...

  16. Implications of the Early X-Ray Afterglow Light Curves of Swift GRBs

    CERN Document Server

    Granot, J; Piran, T; Granot, Jonathan; Konigl, Arieh; Piran, Tsvi

    2006-01-01

    According to current models, gamma-ray bursts (GRBs) are produced when the energy carried by a relativistic outflow is dissipated and converted into radiation. The efficiency of this process, $\\epsilon_\\gamma$, is one of the critical factors in any GRB model. The X-ray afterglow light curves of Swift GRBs show an early stage of flat decay. This has been interpreted as reflecting energy injection. When combined with previous estimates, which have concluded that the kinetic energy of the late ($\\gtrsim 10$ hr) afterglow is comparable to the energy emitted in gamma-rays, this interpretation implies very high values of $\\epsilon_\\gamma \\gtrsim 0.9$. Such a high efficiency is hard to reconcile with most models, including in particular the popular internal-shocks model. We re-analyze the derivation of the kinetic energy from the afterglow X-ray flux and re-examine the resulting estimates of the efficiency. We confirm that, if the flatt decay arises from energy injection and the pre-Swift broad-band estimates of the...

  17. Imprints of Electron-Positron Winds on the Multiwavelength Afterglows of Gamma-ray Bursts

    Science.gov (United States)

    Geng, J. J.; Wu, X. F.; Huang, Y. F.; Li, L.; Dai, Z. G.

    2016-07-01

    Optical rebrightenings in the afterglows of some gamma-ray bursts (GRBs) are unexpected within the framework of the simple external shock model. While it has been suggested that the central engines of some GRBs are newly born magnetars, we aim to relate the behaviors of magnetars to the optical rebrightenings. A newly born magnetar will lose its rotational energy in the form of Poynting-flux, which may be converted into a wind of electron-positron pairs through some magnetic dissipation processes. As proposed by Dai, this wind will catch up with the GRB outflow and a long-lasting reverse shock (RS) would form. By applying this scenario to GRB afterglows, we find that the RS propagating back into the electron-positron wind can lead to an observable optical rebrightening and a simultaneous X-ray plateau (or X-ray shallow decay). In our study, we select four GRBs (i.e., GRB 080413B, GRB 090426, GRB 091029, and GRB 100814A), of which the optical afterglows are well observed and show clear rebrightenings. We find that they can be well interpreted. In our scenario, the spin-down timescale of the magnetar should be slightly smaller than the peak time of the rebrightening, which can provide a clue to the characteristics of the magnetar.

  18. The host-galaxy response to the afterglow of GRB 100901A

    CERN Document Server

    Hartoog, Olga E; Vreeswijk, Paul M; Kaper, Lex; Tanvir, Nial R; Savaglio, Sandra; Berger, Edo; Chornock, Ryan; Covino, Stefano; D'Elia, Valerio; Flores, Hector; Fynbo, Johan P U; Goldoni, Paolo; Gomboc, Andreja; Melandri, Andrea; Pozanenko, Alexei; Schaye, Joop; Postigo, Antonio de Ugarte; Wijers, Ralph A M J

    2013-01-01

    For Gamma-Ray Burst 100901A, we have obtained Gemini-North and Very Large Telescope optical afterglow spectra at four epochs: one hour, one day, three days and one week after the burst, thanks to the afterglow remaining unusually bright at late times. Apart from a wealth of metal resonance lines, we also detect lines arising from fine-structure levels of the ground state of Fe II, and from metastable levels of Fe II and Ni II at the host redshift (z = 1.4084). These lines are found to vary significantly in time. The combination of the data and modelling results shows that we detect the fall of the Ni II 4 F9/2 metastable level population, which to date has not been observed. Assuming that the population of the excited states is due to the UV-radiation of the afterglow, we estimate an absorber distance of a few hundred pc. This appears to be a typical value when compared to similar studies. We detect two intervening absorbers (z = 1.3147, 1.3179). Despite the wide temporal range of the data, we do not see sign...

  19. Intrinsic Depletion or Not

    DEFF Research Database (Denmark)

    Klösgen, Beate; Bruun, Sara; Hansen, Søren;

    with an AFM (2).    The intuitive explanation for the depletion based on "hydrophobic mismatch" between the obviously hydrophilic bulk phase of water next to the hydrophobic polymer. It would thus be an intrinsic property of all interfaces between non-matching materials. The detailed physical interaction path......  The presence of a depletion layer of water along extended hydrophobic interfaces, and a possibly related formation of nanobubbles, is an ongoing discussion. The phenomenon was initially reported when we, years ago, chose thick films (~300-400Å) of polystyrene as cushions between a crystalline...

  20. A burst in a wind bubble and the impact on baryonic ejecta: high-energy gamma-ray flashes and afterglows from fast radio bursts and pulsar-driven supernova remnants

    Science.gov (United States)

    Murase, Kohta; Kashiyama, Kazumi; Mészáros, Peter

    2016-09-01

    Tenuous wind bubbles, which are formed by the spin-down activity of central compact remnants, are relevant in some models of fast radio bursts (FRBs) and superluminous supernovae (SNe). We study their high-energy signatures, focusing on the role of pair-enriched bubbles produced by young magnetars, rapidly rotating neutron stars, and magnetized white dwarfs. (i) First, we study the nebular properties and the conditions allowing for escape of high-energy gamma-rays and radio waves, showing that their escape is possible for nebulae with ages of ≳10-100 yr. In the rapidly rotating neutron star scenario, we find that radio emission from the quasi-steady nebula itself may be bright enough to be detected especially at sub-mm frequencies, which is relevant as a possible counterpart of pulsar-driven SNe and FRBs. (ii) Secondly, we consider the fate of bursting emission in the nebulae. We suggest that an impulsive burst may lead to a highly relativistic flow, which would interact with the nebula. If the shocked nebula is still relativistic, pre-existing non-thermal particles in the nebula can be significantly boosted by the forward shock, leading to short-duration (maybe millisecond or longer) high-energy gamma-ray flashes. Possible dissipation at the reverse shock may also lead to gamma-ray emission. (iii) After such flares, interactions with the baryonic ejecta may lead to afterglow emission with a duration of days to weeks. In the magnetar scenario, this burst-in-bubble model leads to the expectation that nearby (≲10-100 Mpc) high-energy gamma-ray flashes may be detected by the High-Altitude Water Cherenkov Observatory and the Cherenkov Telescope Array, and the subsequent afterglow emission may be seen by radio telescopes such as the Very Large Array. (iv) Finally, we discuss several implications specific to FRBs, including constraints on the emission regions and limits on soft gamma-ray counterparts.

  1. Intrinsic Josephson effects on superconducting films

    CERN Document Server

    Chana, O S

    2002-01-01

    Films of the high-T sub c superconductor Tl sub 2 Ba sub 2 CaCu sub 2 O sub 8 with the crystal c-axis misaligned from the substrate normal have been used to make intrinsic Josephson junctions. The copper-oxide layers in the cuprate superconductor are weakly coupled in the c-direction. This weak interplanar coupling is analogous to superconductor- insulator-superconductor stacks parallel to the c-direction in the film and this maps out to a series array of intrinsic Josephson junctions. A novel device geometry has been used to exploit this and series arrays of intrinsic Josephson junctions have been fabricated. The junctions are optimised in quality and have a high and critical-current- independent value for the product of the critical current and normal state resistance. The temperature dependence of the critical current fits the Ambegaokar-Baratoff theory for SIS tunnelling. X-band emission at around 12 GHz has been detected from the intrinsic Josephson bridge at 103 K. This confirms that the junctions are s...

  2. Modeling total reduced sulfur and sulfur dioxide emissions from a kraft recovery boiler using an artificial neural network, and, Investigating volatile organic compounds in an urban intermountain valley using a TD/GC/MS methodology and intrinsic tracer molecules

    Science.gov (United States)

    Wrobel, Christopher Louis

    2000-11-01

    Back-propagation neural networks were trained to predict total reduced sulfur (TRS) and SO2 emissions from kraft recovery boiler operational data. A 0.721 coefficient of correlation was achieved between actual and predicted sulfur emissions on test data withheld from network training. The artificial neural network (ANN) models found an inverse, linear relationship between TRS/SO2 emissions and percent opacity. A number of relationships among operating parameters and sulfur emissions were identified by the ANN models. These relationships were used to formulate strategies for reducing sulfur emissions. Disagreement between ANN model predictions on a subsequent data set revealed an additional scenario for sulfur release not present in the training data. ANN modeling was demonstrated to be an effective tool for analyzing process variables when balancing productivity and environmental concerns. Five receptor sites distributed in the Missoula Valley, Montana, were employed to investigate possible VOC (benzene, 2,3,4-trimethylpentane, toluene, ethylbenzene, m-/p-xylene, o-xylene, naphthalene, acetone, chloroform, α-pinene, β-pinene, p-cymene and limonene) sources. The most dominant source of VOCs was found to be vehicle emissions. Furthermore, anthropogenic sources of terpenoids overwhelmed biogenic emissions, on a local scale. Difficulties correlating wind direction and pollutant levels could be explained by wind direction variability, low wind speed and seasonally dependent meteorological factors. Significant evidence was compiled to support the use of p-cymene as a tracer molecule for pulp mill VOC emissions. Apportionment techniques using o-xylene and p-cymene as tracers for automobile and pulp mill emissions, respectively, were employed to estimate each source's VOC contribution. Motor vehicles were estimated to contribute between 56 and 100 percent of the aromatic pollutants in the Missoula Valley airshed, depending upon the sampling location. Pulp mill emissions

  3. Intrinsically Disordered Energy Landscapes

    Science.gov (United States)

    Chebaro, Yassmine; Ballard, Andrew J.; Chakraborty, Debayan; Wales, David J.

    2015-05-01

    Analysis of an intrinsically disordered protein (IDP) reveals an underlying multifunnel structure for the energy landscape. We suggest that such ‘intrinsically disordered’ landscapes, with a number of very different competing low-energy structures, are likely to characterise IDPs, and provide a useful way to address their properties. In particular, IDPs are present in many cellular protein interaction networks, and several questions arise regarding how they bind to partners. Are conformations resembling the bound structure selected for binding, or does further folding occur on binding the partner in a induced-fit fashion? We focus on the p53 upregulated modulator of apoptosis (PUMA) protein, which adopts an -helical conformation when bound to its partner, and is involved in the activation of apoptosis. Recent experimental evidence shows that folding is not necessary for binding, and supports an induced-fit mechanism. Using a variety of computational approaches we deduce the molecular mechanism behind the instability of the PUMA peptide as a helix in isolation. We find significant barriers between partially folded states and the helix. Our results show that the favoured conformations are molten-globule like, stabilised by charged and hydrophobic contacts, with structures resembling the bound state relatively unpopulated in equilibrium.

  4. Gamma-ray burst afterglows as probes of their host galaxies and the cosmos

    Science.gov (United States)

    Cucchiara, Antonino

    2010-12-01

    Gamma-ray Bursts (GRBs) represent the sole class of catastrophic phenomena seen over almost the entire history of the Universe. Their extreme luminosities in high energy gamma-ray radiation make them readily detectable, even with relatively small satellite-based detectors, out to the earliest cosmic epochs. Moreover, the brilliance of their fading afterglow light, routinely observed in X-ray, optical, near-infrared, and radio wavelengths, allows them to be exploited -- for hours, days, or weeks -- as cosmic lighthouses, probing the conditions of gas and dust along the line of sight, through their host galaxies and the cosmos at large. Since the November 2004 launch of Swift, this GRB-focused NASA mission has discovered more than 500 GRBs, in almost all cases reporting the burst coordinates to ground-based observers within seconds of the event. The availability of prompt burst positions from Swift, combined with promptly-reported flux measurements from instruments on Swift and an array of ground-based robotic telescopes, have enabled targeted spectroscopic campaigns that have gathered detailed observations of the young, bright afterglows of hundreds of these events. This thesis reports the results of my own efforts over the past 5 years, analyzing imaging and spectroscopic observations of Swift-detected GRBs as triggered according to my own requests, or as gathered from public data archives. In Chapter 2, I discuss our follow-up campaign for GRB090429B, one of our best "extreme redshift" (z > 8) candidates. This burst followed closely on the spectroscopicallyconfirmed z = 8.2 GRB090423, and our multiwavelength observations and SED modeling demonstrate the value and limitation of such studies, in cases where a spectroscopic redshift cannot be gathered in a timely fashion. I also address the importance of such extreme-redshift events from a cosmological perspective. In Chapter 3, I use high-resolution GRB afterglow spectra to study the properties of intervening

  5. A unifying view of Gamma Ray Burst Afterglows

    CERN Document Server

    Ghisellini, G; Ghirlanda, G; Celotti, A

    2008-01-01

    We selected a sample of 33 Gamma Ray Bursts (GRBs) detected by Swift, with known redshift and optical extinction at the host frame. For these, we constructed the de-absorbed and K-corrected X-ray and optical rest frame light curves. These are modelled as the sum of two components: emission from the forward shock due to the interaction of a fireball with the circum-burst medium and an additional component, treated in a completely phenomenological way. The latter can be identified, among other possibilities, as "late prompt" emission produced by a long lived central engine with mechanisms similar to those responsible for the production of the "standard" early prompt radiation. Apart from flares or re-brightenings, that we do not model, we find a good agreement with the data, despite of their complexity and diversity. Although based in part on a phenomenological model with a relatively large number of free parameters, we believe that our findings are a first step towards the construction of a more physical scena...

  6. MAGIC upper limits on the GRB 090102 afterglow

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Babic, A; Bangale, P; de Almeida, U Barres; Barrio, J A; González, J Becerra; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Fidalgo, D Carreto; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Mendez, C Delgado; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Eisenacher, D; Elsaesser, D; Farina, E; Ferenc, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Giavitto, G; Godinović, N; Muñoz, A González; Gozzini, S R; Hadasch, D; Hayashida, M; Herrero, A; Hildebrand, D; Hose, J; Hrupec, D; Idec, W; Kadenius, V; Kellermann, H; Knoetig, M L; Kodani, K; Konno, Y; Krause, J; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lewandowska, N; Lindfors, E; Lombardi, S; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Meucci, M; Miranda, J M; Mirzoyan, R; Moralejo, A; Munar-Adrover, P; Nakajima, D; Niedzwiecki, A; Nilsson, K; Nishijima, K; Nowak, N; Orito, R; Overkemping, A; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Partini, S; Persic, M; Prada, F; Moroni, P G Prada; Prandini, E; Preziuso, S; Puljak, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Rügamer, S; Saggion, A; Saito, T; Saito, K; Salvati, M; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Stamatescu, V; Stamerra, A; Steinbring, T; Storz, J; Sun, S; Surić, T; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Thaele, J; Tibolla, O; Torres, D F; Toyama, T; Treves, A; Vogler, P; Wagner, R M; Zandanel, F; Zanin, R; Bouvier, A; Tajima, H; Longo, F

    2013-01-01

    Indications of a GeV component in the emission from GRBs are known since the EGRET observations during the 1990's and they have been confirmed by the data of the Fermi satellite. These results have, however, shown that our understanding of GRB physics is still unsatisfactory. The new generation of Cherenkov observatories and in particular the MAGIC telescope, allow for the first time the possibility to extend the measurement of GRBs from several tens up to hundreds of GeV energy range. Both leptonic and hadronic processes have been suggested to explain the possible GeV/TeV counterpart of GRBs. Observations with ground-based telescopes of very high energy photons (E>30 GeV) from these sources are going to play a key role in discriminating among the different proposed emission mechanisms, which are barely distinguishable at lower energies. MAGIC telescope observations of the GRB 090102 (z=1.547) field and Fermi Large Area Telescope (LAT) data in the same time interval are analysed to derive upper limits of the ...

  7. Active species in N{sub 2} and N{sub 2}-O{sub 2} afterglows for surface treatments

    Energy Technology Data Exchange (ETDEWEB)

    Ricard, A; Villeger, S [LAPLACE, University Paul Sabatier, CNRS, 118 route de Narbonne 31062 Toulouse (France); Pointu, A M [LPGP, University Paris-Sud, 91405 Orsay (France); Canal, C, E-mail: ricard@laplace.univ-tlse.f [Pharmacy and Pharmaceutical Technology Dpt, University of Barcelona, Avda. Joan XXIII s/n 08028 Barcelona (Spain)

    2010-01-01

    Production of active species is studied in N{sub 2} and in N{sub 2}-O{sub 2} afterglows of electrical discharges at low and atmospheric gas pressures. They are produced in microwave discharges in a large range of gas pressures from a few Torr to 100 Torr and in corona discharges at atmospheric gas pressure. The active species in N{sub 2} afterglows are the N-atoms which are in the range of a few percents in the afterglows. The effect of O{sub 2} molecules in low percentages in low pressure N{sub 2}microwave plasmas and as impurity in corona N{sub 2} discharges is specially analysed. The interaction of N and O-atoms with surfaces is studied for bacteria decontamination and for transmission of N-atoms though porous membranes. The processes of bacteria decontamination in N{sub 2}-O{sub 2} afterglows are described for low pressure microwave and atmospheric pressure corona discharges. Transmission of N-atoms through porous membranes is studied at medium pressure (10-100 Torr) microwave afterglows.

  8. Discovery and redshift of an optical afterglow in 71 square degrees iPTF13bxl and GRB 130702A

    CERN Document Server

    Singer, Leo P; Kasliwal, Mansi M; Perley, Daniel A; Ofek, Eran O; Brown, Duncan A; Nugent, Peter E; Kulkarni, S R; Corsi, Alessandra; Frail, Dale A; Bellm, Eric; Mulchaey, John; Arcavi, Iair; Barlow, Tom; Bloom, Joshua S; Cao, Yi; Gehrels, Neil; Horesh, Assaf; Masci, Frank J; McEnery, Julie; Rau, Arne; Surace, Jason A; Yaron, Ofer

    2013-01-01

    We report the discovery of the optical afterglow of the gamma-ray burst (GRB) 130702A, identified upon searching 71 square degrees surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization. Discovered and characterized by the intermediate Palomar Transient Factory (iPTF), iPTF13bxl is the first afterglow discovered solely based on a GBM localization. Real-time image subtraction, machine learning, human vetting, and rapid response multi-wavelength follow-up enabled us to quickly narrow a list of 27,004 optical transient candidates to a single afterglow-like source. Detection of a new, fading X-ray source by Swift and a radio counterpart by CARMA and the VLA confirmed the association between iPTF13bxl and GRB 130702A. Spectroscopy with the Magellan and Palomar 200-inch telescopes showed the afterglow to be at a redshift of z=0.145, placing GRB 130702A among the lowest redshift GRBs detected to date. The prompt gamma-ray energy release and afterglow luminosity are intermediate between typical cosmological...

  9. Gaussian Intrinsic Entanglement

    Science.gov (United States)

    Mišta, Ladislav; Tatham, Richard

    2016-12-01

    We introduce a cryptographically motivated quantifier of entanglement in bipartite Gaussian systems called Gaussian intrinsic entanglement (GIE). The GIE is defined as the optimized mutual information of a Gaussian distribution of outcomes of measurements on parts of a system, conditioned on the outcomes of a measurement on a purifying subsystem. We show that GIE vanishes only on separable states and exhibits monotonicity under Gaussian local trace-preserving operations and classical communication. In the two-mode case, we compute GIE for all pure states as well as for several important classes of symmetric and asymmetric mixed states. Surprisingly, in all of these cases, GIE is equal to Gaussian Rényi-2 entanglement. As GIE is operationally associated with the secret-key agreement protocol and can be computed for several important classes of states, it offers a compromise between computable and physically meaningful entanglement quantifiers.

  10. Intrinsic Time Quantum Gravity

    CERN Document Server

    Yu, Hoi Lai

    2016-01-01

    Correct identification of the true gauge symmetry of General Relativity being 3d spatial diffeomorphism invariant(3dDI) (not the conventional infinite tensor product group with principle fibre bundle structure), together with intrinsic time extracted from clean decomposition of the canonical structure yields a self-consistent theory of quantum gravity. A new set of fundamental commutation relations is also presented. The basic variables are the eight components of the unimodular part of the spatial dreibein and eight SU(3) generators which correspond to Klauder's momentric variables that characterize a free theory of quantum gravity. The commutation relations are not canonical, but have well defined group theoretical meanings. All fundamental entities are dimensionless; and the quantum wave functionals are preferentially in the dreibein representation. The successful quantum theory of gravity involves only broad spectrum of knowledge and deep insights but no exotic idea.

  11. GeV emission from short Gamma-Ray Bursts: the case of GRB 081024B

    CERN Document Server

    Corsi, Alessandra; Piro, Luigi

    2009-01-01

    We investigate the origin of the high energy tail detected by Fermi/LAT in the short GRB 081024B through synchrotron and self-Compton emission in either the internal or external shock models. In the internal shock scenario, we explore the possibility of generating the high energy photons directly through synchrotron process, or through inverse Compton emission in which target photons are synchrotron photons produced in internal shocks taking place either in the short prompt phase, or in a lately emitted shell (delayed internal shocks). In the external shock scenario, we consider the possibility of the high energy tail being the extension of the afterglow synchrotron emission, or alternatively the inverse Compton component associated to the afterglow synchrotron photons. For the internal shock scenario we conclude that, given the constraints set by the observations on the prompt emission spectrum, only an inverse Compton component from delayed internal shocks can accommodate the presence of a high energy tail ...

  12. The Gamma-ray Afterglows of Tidal Disruption Events

    CERN Document Server

    Chen, Xian; Guillochon, James

    2015-01-01

    A star wandering too close to a supermassive black hole (SMBH) will be tidally disrupted. Previous studies of such "tidal disruption event" (TDE) mostly focus on the stellar debris that are bound to the system, because they give rise to luminous flares. On the other hand, half of the stellar debris in principle are unbound and can steam to a great distance, but so far there is no clear evidence that this "unbound debris steam" (UDS) exists. Motivated by the fact that the circum-nuclear region around SMBHs is usually filled with dense molecular clouds (MCs), here we investigate the observational signatures resulting from the collision between an UDS and a MC, which is likely to happen hundreds of years after a TDE. We focus on $\\gamma$-ray emission ($0.1-10^5$ GeV), which comes from the encounter of shock-accelerated cosmic rays with background protons and, more importantly, is not subject to extinction. We show that because of the high proton density inside the MC, the peak $\\gamma$-ray luminosity is at least...

  13. A CORRELATED STUDY OF OPTICAL AND X-RAY AFTERGLOWS OF GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Li, Liang; Ryde, Felix [Department of Physics, KTH Royal Institute of Technology, SE-106 91 Stockholm (Sweden); Wu, Xue-Feng [Chinese Center for Antarctic Astronomy, Chinese Academy of Sciences, Nanjing 210008 (China); Huang, Yong-Feng; Tang, Qing-Wen; Geng, Jin-Jun [Department of Astronomy, Nanjing University, Nanjing 210093, Jiangsu (China); Wang, Xiang-Gao; Liang, En-Wei [GXU-NAOC Center for Astrophysics and Space Sciences, Department of Physics, Guangxi University, Nanjing 530004 (China); Liang, Yun-Feng [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Zhang, Bin-Bin [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Wang, Yu [Dip. di Fisica and ICRA, Sapienza Universit di Roma, Piazzale Aldo Moro 5, I-00185 Rome (Italy); Wei, Jian-Yan [National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 (China); Zhang, Bing, E-mail: fryde@kth.se, E-mail: liang.li@fysik.su.se [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States)

    2015-05-20

    We study an extensive sample of 87 gamma-ray bursts (GRBs) for which there are well-sampled and simultaneous optical and X-ray light curves. We extract the cleanest possible signal of the afterglow component and compare the temporal behaviors of the X-ray light curve, observed by Swift XRT, and optical data, observed by UVOT and ground-based telescopes for each individual burst. Overall we find that 62% of the GRBs are consistent with the standard afterglow model. When more advanced modeling is invoked, up to 91% of the bursts in our sample may be consistent with the external-shock model. A large fraction of these bursts are consistent with occurring in a constant interstellar density medium (61%) while only 39% of them occur in a wind-like medium. Only nine cases have afterglow light curves that exactly match the standard fireball model prediction, having a single power-law decay in both energy bands that are observed during their entire duration. In particular, for the bursts with chromatic behavior, additional model assumptions must be made over limited segments of the light curves in order for these bursts to fully agree with the external-shock model. Interestingly, for 54% of the X-ray and 40% of the optical band observations, the end of the shallow decay (t{sup ∼−0.5}) period coincides with the jet-break (t{sup ∼−p}) time, causing an abrupt change in decay slope. The fraction of the burst that is consistent with the external-shock model is independent of the observational epochs in the rest frame of GRBs. Moreover, no cases can be explained by the cooling frequency crossing the X-ray or optical band.

  14. VizieR Online Data Catalog: 8 Fermi GRB afterglows follow-up (Singer+, 2015)

    Science.gov (United States)

    Singer, L. P.; Kasliwal, M. M.; Cenko, S. B.; Perley, D. A.; Anderson, G. E.; Anupama, G. C.; Arcavi, I.; Bhalerao, V.; Bue, B. D.; Cao, Y.; Connaughton, V.; Corsi, A.; Cucchiara, A.; Fender, R. P.; Fox, D. B.; Gehrels, N.; Goldstein, A.; Gorosabel, J.; Horesh, A.; Hurley, K.; Johansson, J.; Kann, D. A.; Kouveliotou, C.; Huang, K.; Kulkarni, S. R.; Masci, F.; Nugent, P.; Rau, A.; Rebbapragada, U. D.; Staley, T. D.; Svinkin, D.; Thone, C. C.; de Ugarte Postigo, A.; Urata, Y.; Weinstein, A.

    2015-10-01

    In this work, we present the GBM-iPTF (intermediate Palomar Transient Factory) afterglows from the first 13 months of this project. Follow-up observations include R-band photometry from the P48, multicolor photometry from the P60, spectroscopy (acquired with the P200, Keck, Gemini, APO, Magellan, Very Large Telescope (VLT), and GTC), and radio observations with the Very Large Array (VLA), the Combined Array for Research in Millimeter-wave Astronomy (CARMA), the Australia Telescope Compact Array (ATCA), and the Arcminute Microkelvin Imager (AMI). (3 data files).

  15. Titanium Alloy Surface Modification by a Spatio-Temporal Atmospheric Pressure DBD Afterglow

    Institute of Scientific and Technical Information of China (English)

    E.PANOUSIS; F.CLEMENT; J.F.LOISEAU; N.SPYROU; B.HELD1; J.LARRIEU; F.GUERTON

    2007-01-01

    The experimental work reported here is devoted to the study of the modifications inflicted on the surface of titanium alloy specimens by an atmospheric pressure dielectric barrier discharge(DBD) reactor in both spatial and temporal afterglow conditions.A commercially available (AcXys Technologies) modified reactor system was used for the surface treatment of the TiA6V4 titanium alloy that is widely used in the aeronautical industry.Wettability surface characterisation and XPS analyses are performed to give a macroscopic and microscopic insight to the surface modifications.Best operating conditions,at constant input energy,were obtained for a duty cycle equal to 10%.

  16. Is there a 1998bw-like supernova in the afterglow of gamma ray burst 011121?

    CERN Document Server

    Dado, S; De Rújula, Alvaro; Dado, Shlomo; Dar, Arnon; Rujula, Alvaro De

    2002-01-01

    We use the very simple and successful Cannonball Model (CB) of gamma ray bursts (GRBs) and their afterglows (AGs) to analyze the observations of the strongly extinct optical AG of the relatively nearby GRB 011121, which were made with ground-based telescopes at early times, and with the HST at later time. We show that GRB 011121 was indeed associated with a 1998bw-like supernova at the GRB's redshift, as we had specifically predicted for this GRB before the supernova could be observed.

  17. Afterglow, low-temperature radioluminescence and thermoluminescence of Lu 2O 3:Eu ceramic scintillators

    Science.gov (United States)

    Kappers, L. A.; Bartram, R. H.; Hamilton, D. S.; Brecher, C.; Lempicki, A.

    2005-01-01

    Comparison of thermoluminescence (TL) and scintillation light outputs with continuous gamma-ray excitation reveals that the concentration of deep hole traps in ceramic Lu2O3:Eu, tentatively attributed to anion Frenkel defects, is enhanced by reversible radiation damage. Shallow electron and hole traps are tentatively attributed to surface states at grain boundaries. Electrons in shallow traps serve as non-radiative recombination centers. A model for anomalously persistent afterglow following pulsed X-ray excitation is based on a continuous distribution of hole traps inferred from TL following extended gamma-ray irradiation at -135 °C.

  18. Modeling afterglow rebrightenings by evolving the microphysics in the termination shock

    Science.gov (United States)

    Kong, S. W.; Wong, A. Y. L.; Huang, Y. F.; Cheng, K. S.

    2010-10-01

    Conventionally, long GRBs are thought to be caused by the core collapses of massive stars. During the lifetime of a massive star, a termination shock environment should be produced. Furthermore, the microphysics shock parameters may vary along with the evolution of the fireball. Our numerical simulations indicate that adding the evolution of the microphysics shock parameters in the termination shock can acceptably reproduce the rebrightenings in both the R-band and X-ray afterglow light curves of GRBs, for example GRB 060206, GRB 070311 and GRB 071010A.

  19. Managing GRB afterglows optical/IR observations in the web 2.0 era

    Science.gov (United States)

    Ricci, D.; Nicastro, L.

    2013-07-01

    We present an overview of top internet technologies that can be used to build webtools and rich internet applications for astronomy. The aim is to simplify the data handling, reduction and access, in particular of optical/infrared images collected by traditional, automatic or robotic telescopes. These tools are particularly suitable for real-time management of GRB afterglow observations. Using these technologies we are developing a web-based images database management system. We present available features and discuss further improvements to the mentioned system.

  20. Intrinsic Angular Momentum of Light.

    Science.gov (United States)

    Santarelli, Vincent

    1979-01-01

    Derives a familiar torque-angular momentum theorem for the electromagnetic field, and includes the intrinsic torques exerted by the fields on the polarized medium. This inclusion leads to the expressions for the intrinsic angular momentum carried by the radiation traveling through a charge-free medium. (Author/MA)

  1. Time generated by intrinsic observers

    CERN Document Server

    Svozil, Karl

    2009-01-01

    We shortly review the construction of knowledge by intrinsic observers. Intrinsic observers are embedded in a system and are inseparable parts thereof. The intrinsic viewpoint has to be contrasted with an extrinsic, "God's eye" viewpoint, from which the system can be observed externally without in any way changing it. This epistemological distinction has concrete, formalizable consequences. One consequence is the emergence of "complementarity" for intrinsic observers, even if the underlying system is totally deterministic (computable). Another consequence is the appearence of time and inertial frames for intrinsic observers. The necessary operational techniques are developed in the context of Cellular Automata. We finish with a somewhat speculative question. Given space-time frames generated by clocks which use sound waves for synchronization; why could supersonic travel not cause time paradoxes?

  2. Intrinsic Correlations for Flaring Blazars Detected by Fermi

    Science.gov (United States)

    Fan, J. H.; Yang, J. H.; Xiao, H. B.; Lin, C.; Constantin, D.; Luo, G. Y.; Pei, Z. Y.; Hao, J. M.; Mao, Y. W.

    2017-02-01

    Blazars are an extreme subclass of active galactic nuclei. Their rapid variability, luminous brightness, superluminal motion, and high and variable polarization are probably due to a beaming effect. However, this beaming factor (or Doppler factor) is very difficult to measure. Currently, a good way to estimate it is to use the timescale of their radio flares. In this Letter, we use multiwavelength data and Doppler factors reported in the literature for a sample of 86 flaring blazars detected by Fermi to compute their intrinsic multiwavelength data and intrinsic spectral energy distributions and investigate the correlations among observed and intrinsic data. Quite interestingly, intrinsic data show a positive correlation between luminosity and peak frequency, in contrast with the behavior of observed data, and a tighter correlation between γ-ray luminosity and the lower-energy ones. For flaring blazars detected by Fermi, we conclude that (1) observed emissions are strongly beamed; (2) the anti-correlation between luminosity and peak frequency from the observed data is an apparent result, the correlation between intrinsic data being positive; and (3) intrinsic γ-ray luminosity is strongly correlated with other intrinsic luminosities.

  3. Off-axis emission of short γ-ray bursts and the detectability of electromagnetic counterparts of gravitational-wave-detected binary mergers

    Science.gov (United States)

    Lazzati, Davide; Deich, Alex; Morsony, Brian J.; Workman, Jared C.

    2017-10-01

    We present calculations of the wide angle emission of short-duration gamma-ray bursts from compact binary merger progenitors. Such events are expected to be localized by their gravitational wave emission, fairly irrespective of the orientation of the angular momentum vector of the system, along which the gamma-ray burst outflow is expected to propagate. We show that both the prompt and afterglow emission are dim and challenging to detect for observers lying outside the cone within which the relativistic outflow is propagating. If the jet initially propagates through a baryon contaminated region surrounding the merger site, however, a hot cocoon forms around it. The cocoon subsequently expands quasi-isotropically producing its own prompt emission and external shock powered afterglow. We show that the cocoon prompt emission is detectable by Swift BAT and Fermi GBM. We also show that the cocoon afterglow peaks a few hours to a few days after the burst and is detectable for up to a few weeks at all wavelengths. The timing and brightness of the transient are however uncertain due to their dependence on unknown quantities such as the density of the ambient medium surrounding the merger site, the cocoon energy and the cocoon Lorentz factor. For a significant fraction of the gravitationally detected neutron-star-binary mergers, the cocoon afterglow could possibly be the only identifiable electromagnetic counterpart, at least at radio and X-ray frequencies.

  4. Stationary-Afterglow measurements of dissociative recombination of H2D+ and HD2+ ions

    Science.gov (United States)

    Dohnal, Petr; Kalosi, Abel; Plasil, Radek; Johnsen, Rainer; Glosik, Juraj

    2016-09-01

    Binary recombination rate coefficients of H2D+ and HD2+ ions have been measured at a temperature of 80 K in an afterglow plasma experiment in which the fractional abundances of H3+, H2D+, HD2+, and D3+ ions were varied by adjusting the [D2]/([D2] + [H2]) ratio of the neutral gas. The fractional abundances of the four ion species during the afterglow and their rotational states were determined in situ by continuous-wave cavity ring-down absorption spectroscopy (CRDS), using overtone transitions from the ground vibrational states of the ions. The experimentally determined recombination rate coefficients will be compared to results of advanced theoretical calculations and to the known H3+ and D3+ recombination rate coefficients. We conclude that the recombination coefficients depend only weakly on the isotopic composition. Astrophysical implications of the measured recombination rate coefficients will be also discussed. Work supported by: Czech Science Foundation projects GACR 14-14649P, GACR 15-15077S, GACR P209/12/0233, and by Charles University in Prague Project Nr. GAUK 692214.

  5. Swift observations of GRB 060614: an anomalous burst with a well behaved afterglow

    CERN Document Server

    Mangano, V; Malesani, D; Troja, E; Chincarini, G; Zhang, B; La Parola, V; Brown, P J; Burrows, D N; Campana, S; Capalbi, M; Cusumano, G; Della Valle, M; Gehrels, N; Giommi, P; Grupe, D; Guidorzi, C; Mineo, T; Moretti, A; Osborne, J P; Pandey, S B; Perri, M; Romano, P; Roming, P W A; Tagliaferri, G

    2007-01-01

    GRB 060614 is a remarkable GRB observed by Swift with puzzling properties, which challenge current progenitor models. The lack of any bright SN down to very strict limits and the vanishing spectral lags are typical of short GRBs, strikingly at odds with the long (102s) duration of this event. Here we present spectral and temporal analysis of the Swift observations. We show that the burst presents standard optical, UV and X-ray afterglows. An achromatic break is observed simultaneously in optical and X-rays, at a time consistent with the break in the R-band light curve measured by the VLT. The achromatic behaviour and the consistent post-break decay slopes make GRB 060614 one of the best examples of a jet break for a Swift burst. The optical, UV and X-rays afterglow light curves have also an earlier break at ~30 ks. In the optical, there is strong spectral evolution around this break, suggesting the passage of a break frequency through the optical/UV band. The very blue spectrum at early times and the trend in...

  6. $\\gamma$-Ray Burst Afterglows Effects of Radiative Corrections and Nonuniformity of the Surrounding Medium

    CERN Document Server

    Dai, Z G

    1998-01-01

    The afterglow of a gamma-ray burst (GRB) is commonly thought to be due to continuous deceleration of a relativistically expanding fireball in the surrounding medium. Assuming that the expansion of the fireball is adiabatic and that the density of the medium is a power-law function of shock radius, viz., $n_{ext}\\propto R^{-k}$, we analytically study the effects of the first-order radiative correction and the nonuniformity of the medium on a GRB afterglow. We first derive a new relation among the observed time, the shock radius and the fireball's Lorentz factor: $t_\\oplus=R/4(4-k)\\gamma^2c$, and also derive a new relation among the comoving time, the shock radius and the fireball's Lorentz factor: $t_{co}=2R/(5-k)\\gamma c$. We next study the evolution of the fireball by using the analytic solution of Blandford and McKee (1976). The radiation losses may not significantly influence this evolution. We further derive new scaling laws both between the X-ray flux and observed time and between the optical flux and ob...

  7. GRB 070125 and the environments of spectral-line poor afterglow absorbers

    CERN Document Server

    De Cia, A; Wiersema, K; van der Horst, A J; Vreeswijk, P M; Björnsson, G; Postigo, A de Ugarte; Jakobsson, P; Levan, A J; Rol, E; Schulze, S; Tanvir, N R

    2011-01-01

    GRB 070125 is among the most energetic bursts detected and the most extensively observed so far. Nevertheless, unresolved issues are still open in the literature on the physics of the afterglow and on the GRB environment. In particular, GRB 070125 was claimed to have exploded in a galactic halo environment, based on the uniqueness of the optical spectrum and the non-detection of an underlying host galaxy. In this work we collect all publicly available data and address these issues by modelling the NIR-to-X-ray spectral energy distribution (SED) and studying the high signal-to-noise VLT/FORS afterglow spectrum in comparison with a larger sample of GRB absorbers. The SED reveals a synchrotron cooling break in the UV, low equivalent hydrogen column density and little reddening caused by a LMC- or SMC-type extinction curve. From the weak MgII absorption at z=1.5477 in the spectrum, we derived logN(MgII)=12.96+0.13-0.18 and upper limits on the ionic column density of several metals. These suggest that the GRB abso...

  8. The Angular Size and Proper Motion of the Afterglow of GRB 030329

    CERN Document Server

    Taylor, G B; Berger, E; Kulkarni, S R

    2004-01-01

    The bright, nearby (z=0.1685) gamma-ray burst of 29 March 2003 has presented us with the first opportunity to directly image the expansion of a GRB. This burst reached flux density levels at centimeter wavelengths more than 50 times brighter than any previously studied event. Here we present the results of a VLBI campaign using the VLBA, VLA, Green Bank, Effelsberg, Arecibo, and Westerbork telescopes that resolves the radio afterglow of GRB 030329 and constrains its rate of expansion. The size of the afterglow is found to be \\~0.07 mas (0.2 pc) 25 days after the burst, and 0.17 mas (0.5 pc) 83 days after the burst, indicating an average velocity of 3-5 c. This expansion is consistent with expectations of the standard fireball model. We measure the projected proper motion of GRB 030329 in the sky to <0.3 mas in the 80 days following the burst. In observations taken 52 days after the burst we detect an additional compact component at a distance from the main component of 0.28 +/- 0.05 mas (0.80 pc). The pres...

  9. Effects of the offset term in experimental simulation on afterglow decay curve.

    Science.gov (United States)

    Tsai, Chi-Yang; Lin, Jeng-Wen; Huang, Yih-Ping; Huang, Yung-Chieh

    2014-01-01

    This study examines the effect of the offset term in a multiple single exponential equation that fits into experimental afterglow decay curve data for material applications. For afterglow materials applied and attached to structures, the inclusion of this offset term may reduce the values of the calculated decay times, τ i , and enlarge the time invariant constants, A i , in the associated equation compared to theoretically perfect test conditions. Using a set of experimental data obtained from a lab under dim light, adjustments can be made to calculate the required parameters for an equation without the offset term. This study uses mathematical simulations and lab tests to support our thesis and crosslink test results generated from different ambient light conditions. This paper defines the offset ratio as the ratio of the offset value, I 0, versus the initial light intensity in an equation. This ratio can be used to evaluate possible effects on the calculated parameters of an equation in an associated numerical simulation. The most reliable parameters will have consistent results from the use of multiple single exponential equations, with and without the offset term, in simulations to obtain them in an equation to model a set of data.

  10. Very early multi-color observations of the plateau phase of GRB 041006 afterglow

    CERN Document Server

    Urata, Y; Qiu, Y L; Hu, J; Kuo, P H; Tamagawa, T; Ip, W H; Kinoshita, D; Fukushi, H; Isogai, M; Miyata, T; Nakada, Y; Aoki, T; Soyano, T; Tarusawa, K; Mito, H; Onda, K; Ibrahimov, M; Pozanenko, A; Makishima, K

    2006-01-01

    Observations of the optical afterglow of GRB 041006 with the Kiso Observatory 1.05 m Schmidt telescope, the Lulin Observatory 1.0 m telescope and the Xinglong Observatory 0.6 m telescope. Three-bands (B, V and R) of photometric data points were obtained on 2004 October 6, 0.025-0.329 days after the burst. These very early multi band light curves imply the existence of a color dependent plateau phase. The B-band light curve shows a clear plateau at around 0.03 days after the burst. The R band light curve shows the hint of a plateau, or a possible slope change, at around 0.1 days after the burst. The overall behavior of these multi-band light curves may be interpreted in terms of the sum of two separate components, one showing a monotonic decay the other exhibiting a rising and a falling phase, as described by the standard afterglow model.

  11. REMIR: The REM infrared camera to follow up the early phases of GRBs afterglows

    Science.gov (United States)

    Calzoletti, L.; Melandri, A.; Testa, V.; Antonelli, L. A.; Vitali, F.; D'Alessio, F.; di Paola, A.; Zerbi, F. M.; Chincarini, G.; Cunniffe, R.; Jordan, B.; Rodonò, M.; Conconi, P.; Covino, S.; Cutispoto, G.; Molinari, E.; Tosti, G.; Ross/Rem Team

    2005-07-01

    REMIR is a near-infrared camera, covering the 0.95-2.3 μm range with 5 filters (z,J,H,Ks and H2), mounted at one of the Nasmyth foci of the REM (Rapid Eye Mount) telescope. REM is a fully robotic fast-slewing 60 cm telescope, primarily designed to follow-up the early phases of the afterglow of GRBs detected by dedicated instruments onboard satellites (like SWIFT, a satellite entirely dedicated to GRBs science launched the 12 November 2004). Moreover REM hosts a slitless spectrograph covering the range 0.45-0.95 μm, with 30 sample points and with the possibility to perform broad-band V,R,I photometry (ROSS, REM Optical Slitless Spectrograph). The main task of REMIR is to perform realtime NIR observations of GRBs detected by gamma-ray monitors onboard satellites, looking for any possible infrared transient source. As soon as a transient source is detected in the IR images, larger telescopes are promptly alerted to perform early spectroscopy of the afterglow. All the above operations are performed in a fully automatic way and without any human supervision. We present the results of on-site tests that have been done to characterize the REMIR camera and the performances of the dedicated reduction pipeline AQuA (Automatic Quick Analysis), suited for fast transients detection.

  12. The redshift and afterglow of the extremely energetic gamma-ray burst GRB 080916C

    CERN Document Server

    Greiner, J.; Kruehler, T.; Kienlin, A.v.; Rau, A.; Sari, R.; Fox, Derek B.; Kawai, N.; Afonso, P.; Ajello, M.; Berger, E.; Cenko, S.B.; Cucchiara, A.; Filgas, R.; Klose, S.; Yoldas, A.Kuepue; Lichti, G.G.; Loew, S.; McBreen, S.; Nagayama, T.; Rossi, A.; Sato, S.; Szokoly, G.; Yoldas, A.; Zhang, X.-L.

    2009-01-01

    The detection of GeV photons from gamma-ray bursts (GRBs) has important consequences for the interpretation and modelling of these most-energetic cosmological explosions. The full exploitation of the high-energy measurements relies, however, on the accurate knowledge of the distance to the events. Here we report on the discovery of the afterglow and subsequent redshift determination of GRB 080916C, the first GRB detected by the Fermi Gamma-Ray Space Telescope with high significance detection of photons at >0.1 GeV. Observations were done with 7-channel imager GROND at the 2.2m MPI/ESO telescope, the SIRIUS instrument at the Nagoya-SAAO 1.4m telescope in South Africa, and the GMOS instrument at Gemini-S. The afterglow photometric redshift of z=4.35+-0.15, based on simultaneous 7-filter observations with the Gamma-Ray Optical and Near-infrared Detector (GROND), places GRB 080916C among the top 5% most distant GRBs, and makes it the most energetic GRB known to date. The detection of GeV photons from such a dista...

  13. Structure of Gamma-Ray Burst jets: intrinsic versus apparent properties

    CERN Document Server

    Salafia, O S; Pescalli, A; Ghirlanda, G; Nappo, F

    2015-01-01

    With this paper we introduce the concept of apparent structure of a GRB jet, as opposed to its intrinsic structure. The latter is customarily defined specifying the functions epsilon(theta) (the energy emitted per jet unit solid angle) and Gamma(theta) (the Lorentz factor of the emitting material); the apparent structure is instead defined by us as the isotropic equivalent energy E_iso(theta_v) as a function of the viewing angle theta_v. We show how to predict the apparent structure of a jet given its intrinsic structure. We find that a Gaussian intrinsic structure yields a power law apparent structure: this opens a new viewpoint on the Gaussian (which can be understood as a proxy for a realistic narrow, well collimated jet structure) as a possible candidate for a quasi-universal GRB jet structure. We show that such a model (a) is consistent with recent constraints on the observed luminosity function of GRBs; (b) implies fewer orphan afterglows with respect to the standard uniform model; (c) can break out the...

  14. Recent progress on intrinsic charm

    Science.gov (United States)

    Hobbs, T. J.

    2017-03-01

    Over the past ˜10 years, the topic of the nucleon's nonperturbative or intrinsic charm (IC) content has enjoyed something of a renaissance, largely motivated by theoretical developments involving quark modelers and PDF-fitters. In this talk I will briefly describe the importance of intrinsic charm to various issues in high-energy phenomenology, and survey recent progress in constraining its overall normalization and contribution to the momentum sum rule of the nucleon. I end with the conclusion that progress on the side of calculation has now placed the onus on experiment to unambiguously resolve the proton's intrinsic charm component.

  15. Intrinsic time geometrodynamics: explicit examples

    CERN Document Server

    Lin, Huei-Chen

    2016-01-01

    Intrinsic time quantum geometrodynamics resolved `the problem of time' and bridged the deep divide between quantum mechanics and canonical quantum gravity with a Schrodinger equation which describes evolution in intrinsic time variable. In this formalism, Einstein's general relativity is a particular realization of a wider class of theories. Explicit classical black hole and cosmological solutions and the motion of test particles are derived and analyzed in this work in the context of constant three-curvature solutions in intrinsic time geometrodynamics; and we exemplify how this formalism yields results which agree with the predictions of Einstein's theory.

  16. Superelastic collisions under low temperature plasma and afterglow conditions: A golden rule to estimate their quantitative effects

    Energy Technology Data Exchange (ETDEWEB)

    D' Ammando, Giuliano, E-mail: g.dammando@chimica.uniba.it; Capitelli, Mario, E-mail: mario.capitelli@ba.imip.cnr.it [CNR-IMIP, Via Amendola 122/D, 70126 Bari (Italy); Dipartimento di Chimica, Universitá di Bari, Via Orabona 4, 70125 Bari (Italy); Colonna, Gianpiero, E-mail: gianpiero.colonna@ba.imip.cnr.it; Laricchiuta, Annarita, E-mail: annarita.laricchiuta@ba.imip.cnr.it [CNR-IMIP, Via Amendola 122/D, 70126 Bari (Italy)

    2015-03-15

    A simple equation describing the formation of plateaux induced by superelastic collisions in the electron energy distribution function (EEDF) of low temperature and afterglow plasmas is derived. The EEDFs predicted from this equation are in good agreement with those obtained from the numerical solution of the full Boltzmann equation in the presence of excited states.

  17. X-ray plateaus followed by sharp drops in GRBs 060413, 060522,060607A and 080330: Further evidences for central engine afterglow from gamma-ray bursts

    Institute of Scientific and Technical Information of China (English)

    Xiao-Hui Zhang

    2009-01-01

    The X-ray afterglows of GRBs 060413, 060522, 060607A and 080330 are characterized by a plateau followed by a very sharp drop. The plateau could be explained within the framework of the external forward shock model but the sharp drop can not.We interpret the plateau as the afterglows of magnetized central engines, plausibly magnetars. In this model, the X-ray afterglows are powered by the internal magnetic energy dissipation and the sudden drop is caused by the collapse of the magnetar. Accordingly,the X-ray plateau photons should have a high linear polarization, which can be tested by future X-ray polarimetry.

  18. Intrinsic motivation and learning dynamics

    CERN Document Server

    Zgonnikov, Arkady

    2013-01-01

    We investigate the effects of intrinsic motivation on the dynamics of learning processes. We construct a simple model of a single agent adapting to unknown environment. Performing a repeated choice between a number of initially unexplored alternatives, the agent gains rewards for each selected alternative and in doing so gradually comprehends the environment. In our model the agent choice is governed by two stimuli. The traditional extrinsic motive inclines the agent to maximize the cumulative payoff throughout the process, while the second, intrinsic one, biases the agent towards the novel options that she inherently likes. We show that the intrinsic motivation can induce an instability and periodic dynamics of the learning process which is always stationary in the case of selfish, rational agent. Interestingly, the opposite effect can arise as well: when the impact of intrinsic motivation on the agent choice is strong, the equiprobable choice equilibrium strategy becomes stable. Based on the presented resul...

  19. Harmonic structures and intrinsic torsion

    DEFF Research Database (Denmark)

    Conti, Diego; Madsen, Thomas Bruun

    2015-01-01

    We discuss the construction of Sp(2)Sp(1)-structures whose fundamental form is closed. In particular, we find 10 new examples of 8-dimensional nilmanifolds that admit an invariant closed 4-form with stabiliser Sp(2) Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We...... present a thorough investigation of the intrinsic torsion of such structures, leading to the construction of explicit Lie group examples with invariant intrinsic torsion....

  20. Harmonic structures and intrinsic torsion

    DEFF Research Database (Denmark)

    Conti, Diego; Madsen, Thomas Bruun

    We discuss the construction of 8-manifolds with harmonic Sp(2)Sp(1)-structures. In particular, we find 10 new examples of nilmanifolds that admit a closed 4-form Omega whose stabiliser is Sp(2)Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We present a thorough inv...... investigation of the intrinsic torsion of such structures; in addition to the construction of harmonic structures, this analysis leads to explicit Lie group examples with invariant intrinsic torsion....

  1. Tuning the luminescence color and enhancement of afterglow properties of Sr{sub (4−x−y)}Ca{sub x}Ba{sub y}Al{sub 14}O{sub 25}:Eu{sup 2+},Dy{sup 3+} phosphor by adjusting the composition

    Energy Technology Data Exchange (ETDEWEB)

    Luitel, Hom Nath, E-mail: mehomnath@yahoo.com [Faculty of Science and Engineering, Department of Applied Chemistry, Saga University, Honjo-1, Saga, 840-8502 (Japan); Environmental Optical Technology INC, 598-1 Orishikise, Nagasaki, 859-3701 (Japan); Watari, Takanori, E-mail: watarit@cc.saga-u.ac.jp [Faculty of Science and Engineering, Department of Applied Chemistry, Saga University, Honjo-1, Saga, 840-8502 (Japan); Chand, Rumi; Torikai, Toshio; Yada, Mitsunori [Faculty of Science and Engineering, Department of Applied Chemistry, Saga University, Honjo-1, Saga, 840-8502 (Japan); Mizukami, Hiroshi [Environmental Optical Technology INC, 598-1 Orishikise, Nagasaki, 859-3701 (Japan)

    2013-07-01

    Graphical abstract: Excitation and fluorescence emission spectra of three extreme compositions of Ca, Sr and Ba in Sr{sub 4}Al{sub 14}O{sub 25} phosphor (viz. 4CaO·7Al{sub 2}O{sub 3}, 4SrO·7Al{sub 2}O{sub 3} and 4BaO·7Al{sub 2}O{sub 3}) doped with 4 at% Eu{sup 2+} and 8 at% Dy{sup 3+} (inset shows the digital micrograph of corresponding phosphors). -- Highlights: • Bright phosphor, Sr{sub (4−x−y)}Ca{sub x}Ba{sub y}Al{sub 14}O{sub 25}:Eu{sup 2+},Dy{sup 3+}, was synthesized by adjusting the composition. • The solid solubility of Ca and Ba in the Sr{sub 4}Al{sub 14}O{sub 25} host was determined to be 20 and 10 mol%, respectively. • Substituting part of Sr by Ca, the emission color can be well tuned from blue to green. • A white afterglow was observed when 3.2 mol of Sr was substituted by Ca. • The afterglow luminescence was enhanced by 1.5 times by 0.2 mol Ca substitution. -- Abstract: Color point tuning is an important challenge for improving the practical applications of various displays, especially there are very limited white color single hosts that emits in the white spectrum. In this paper, the possibility of color tuning by substituting part of host lattice cation (Sr{sup 2+} ions) by Ca{sup 2+} or Ba{sup 2+} ions in an efficient strontium aluminate phosphor, Sr{sub 4}Al{sub 14}O{sub 25}:Eu{sup 2+},Dy{sup 3+}, is reported and found to be very promising for displays. A detail study by replacing part of Sr{sup 2+} with Ca{sup 2+} or Ba{sup 2+} has been investigated. X-ray diffraction study showed that crystal structure of Sr{sub 4}Al{sub 14}O{sub 25} is preserved up to 20 mol of Ca{sup 2+} ion exchange while it is limited to 10 mol of Ba{sup 2+} ions exchange. Substantial shift in the emission band and color were observed by substitution of Sr{sup 2+} by Ca{sup 2+} or Ba{sup 2+} ions. A bluish-white emission and afterglow was observed at higher Ca{sup 2+} ions substitution. Further, partial Ca{sup 2+} substitutions (up to 0.8 mol) resulted in

  2. EFFECT OF ALKALINE IONS ON THE PHASE EVOLUTION, PHOTOLUMINESCENCE, AND AFTERGLOW PROPERTIES OF SrAl2O4: Eu2+, Dy3+ PHOSPHOR

    Directory of Open Access Journals (Sweden)

    HYUNHO SHIN

    2012-12-01

    Full Text Available A series of SrAl2O4: Eu2+, Dy3+ long-afterglow (LAG phosphors with varying concentration of Li+, Na+ and K+, has been synthesized. The increased concentration of the three types of alkaline ions does not decrease the quantity of the total luminescent phases (SrAl2O4 plus Sr4Al14O25, but a different set of secondary phases has been evoluted for the K+-added series due to the failure of the incorporation of relatively large K+ (1.38 Å to the Sr2+ (1.18 Å site in the hosts, unlike the cases of smaller Li+ (0.76 Å and Na+ (1.02 Å ions. PL excitation, PL emission, and LAG luminescence, are decreased by all investigated alkaline ions, which would be due to the diminished incorporation of Eu2+ and Dy3+ activators into the luminescent hosts by the alkaline ions. For the cases of the Li+ and Na+-added series, the incorporated Li+ or Na+ to the luminescent hosts would also limit the activation of Eu2+ and charge trapping/detrapping of Dy3+ to yield the diminished PL properties and LAG luminescence. The type of defect complex formed by the addition of Li+ and Na+ ions has been deduced and compared with that formed when no alkaline ion is added.

  3. Enhanced afterglow property of BaAl2O4:Eu2+, Dy3+ phosphors by adding Li2CO3

    Science.gov (United States)

    Ma, Junfeng; Fan, Dongxiao; Niu, Bingbing; Lan, Xuena

    BaAl2O4:Eu2+, Dy3+ phosphors with a good long lasting property can be easily obtained via a solid state reaction assisted with Li2CO3. The influence of Li2CO3 quantity on the lattice structure of BaAl2O4:Eu2+, Dy3+ phosphors, their photoluminescence (PL) property, and decaying process was studied by XRD, PL, and afterglow decay measurement, respectively. The results show that incorporating Li2CO3 in preparing process would obviously affect their lattice structure, accompanied by the variation of their luminescent property. With the increase of Li2CO3, their fluorescence property would gradually increase, at m=0.04 (Ba0.96Al2O4:Eu0.012+,Dy0.033+ṡmLi2CO3) reach their maximum emission intensity, and then decrease; but their phosphorescence property would continue to strengthen whether in brightness and decaying time up to m=0.07, and then decrease.

  4. Prompt, early, and afterglow optical observations of five gamma-ray bursts (GRBs 100901A, 100902A, 100905A, 100906A, and 101020A)

    CERN Document Server

    Gorbovskoy, E S; Lipunov, V M; Kornilov, V G; Belinski, A A; Shatskiy, N I; Tyurina, N V; Kuvshinov, D A; Balanutsa, P V; Chazov, V V; Kuznetsov, A; Zimnukhov, D S; Kornilov, M V; Sankovich, A V; Krylov, A; Ivanov, K I; Chvalaev, O; Poleschuk, V A; Konstantinov, E N; Gress, O A; Yazev, S A; Budnev, N M; Krushinski, V V; Zalozhnich, I S; Popov, A A; Tlatov, A G; Parhomenko, A V; Dormidontov, D V; Sennik, V; Yurkov, V V; Sergienko, Yu P; Varda, D; Kudelina, I P; Castro-Tirado, A J; Gorosabel, J; Sánchez--Ramírez, R; Jelinek, M; Tello, J C

    2011-01-01

    We present results of the prompt, early, and afterglow optical observations of five gamma-ray bursts, GRBs 100901A, 100902A, 100905A, 100906A, and 101020A, made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II net), the 1.5-m telescope of Sierra-Nevada Observatory, and the 2.56-m Nordic Optical Telescope. For two sources, GRB 100901A and GRB 100906A, we detected optical counterparts and obtained light curves starting before cessation of gamma-ray emission, at 113 s and 48 s after the trigger, respectively. Observations of GRB 100906A were conducted with two polarizing filters. Observations of the other three bursts gave the upper limits on the optical flux; their properties are briefly discussed. More detailed analysis of GRB 100901A and GRB 100906A supplemented by Swift data provides the following results and indicates different origins of the prompt optical radiation in the two bursts. The light curves patterns and spectral distributions suggest a common production site of the pr...

  5. The extraordinarily bright optical afterglow of GRB 991208 and its host galaxy

    DEFF Research Database (Denmark)

    Castro-Tirado, A.J.; Sokolov, V.V.; Gorosabel, J.;

    2001-01-01

    a massive star origin. The absolute magnitude of the galaxy is M-B = -18.2, well below the knee of the galaxy luminosity function and we derive a star-forming rate of (11.5 +/- 7.1) M-circle dot yr(-1), which is much larger than the present-day rate in our Galaxy. The quasi simultaneous broad......-band photometric spectral energy distribution of the afterglow was determined similar to3.5 day after the burst (Dec. 12.0) implying a cooling frequency ve below the optical band, i.e. supporting a jet model with p = -2.30 as the index of the power-law electron distribution....

  6. Heating and Trapping of Electrons in ECRIS from Scratch to Afterglow

    CERN Document Server

    Heinen, A; Ortjohann, H W; Vitt, C; Andrae, H J

    1999-01-01

    Plasmas in Electron Cyclotron Resonance Ion Sources (ECRIS) are collisionless and can therefore be simulated by just following the motion of electrons in the confining static magnetic and oscillating microwave (MW) electric field of ECRIS. With a powerful algorithm the three-dimensional trajectories of 104 ECR-heated and confined electrons are calculated in a standard ECRIS with a deep minimum of |B| and a new ECRIS with a very flat minimum of |B|. The spatial electron (plasma) densities and electron energy densities deduced from these trajectories yield new and surprising insight in the performance of ECRIS. With computer animation we plan to present: The energy increase of certain electrons on extremely stable trajectories, the power dependence of the electron energy density up to the X-ray collapse, the time dependent build up of the electron density and energy density distributions, and the time evolution of these electron distributions under afterglow conditions.

  7. Afterglow Light Curves of Jetted Gamma-ray Burst Ejecta in Stellar Winds

    Institute of Scientific and Technical Information of China (English)

    Xue-Feng Wu; Zi-Gao Dai; Yong-Feng Huang; Hai-Tao Ma

    2004-01-01

    Optical and radio afterglows arising from shocks by relativistic conical ejecta running into pre-burst massive stellar winds are revisited. Under the homogeneous thin-shell approximation and a realistic treatment for the lateral expansion of jets, our results show that a notable break exists in the optical light curve in most cases we calculated in which the physical parameters are varied within reasonable ranges. For a relatively tenuous wind which cannot decelerate the relativistic jet to cause a light curve break within days, the wind termination shock due to the ram pressure of the surrounding medium occurs at a small radius, namely, a few times 1017 cm. In such a structured wind environment, the jet will pass through the wind within several hours and run into the outer uniform dense medium. The resulting optical light curve flattens with a shallower drop after the jet encounters the uniform medium, and then declines deeply, triggered by runaway lateral expansion.

  8. GRB Afterglow Blast Wave Encountering Sudden Circumburst Density Change Produces No Flares

    CERN Document Server

    Gat, Ilana; MacFadyen, Andrew

    2013-01-01

    Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called ram, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreadin...

  9. No flares from GRB afterglow blast waves encountering sudden circumburst density change

    CERN Document Server

    Gat, Ilana; MacFadyen, Andrew

    2013-01-01

    Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreadin...

  10. Gamma-Ray Burst Afterglows with Energy Injection: Homogeneous VersusWind External Media

    Institute of Scientific and Technical Information of China (English)

    王伟; 戴子高

    2001-01-01

    Assuming an adiabatic evolution of a gamma-ray burst (GRB) fireball interacting with an external medium,we calculate the hydrodynamics of the fireball with an energy injection from a strongly magnetic millisecond pulsar through magnetic dipole radiation, and obtain the light curve of the optical afterglow from the fireball by synchrotron radiation. The results are given both for an homogeneous external medium and for a wind ejected by GRB progenitor. Our calculations are also available in both ultra-relativistic and non-relativistic phases.Furthermore, the observed R-band light curve of GRB000301C can be well fitted in our model, which might provide a probe of the properties of GRB progenitors.

  11. Flowing afterglow spectroscopy: an ultrasensitive probe into solid-phase decomposition kinetics. [TATB and NQ

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, G.W.; Andrews, G.H. Jr.

    1979-01-01

    The thermal-decomposition kinetics of high explosives are important to manufacturers and these dangerous materials from the standpoint of processing and storage. Low-temperature kinetics (20 to 200/sup 0/C) are difficult to obtain. Either extremely sensitive analytical techniques must be employed or very large amounts of material must be tested by less sensitive methods. The latter technique has the disadvantage that when sensitive explosives or propellants are so tested, catastrophic reaction can result in the destruction of expensive equipment, and the time involved in testing may be extremely long. The flowing-afterglow method, proposed here, utilizes small explosive samples and an ultra-sensitive analytical approach. The paper describes the technique in detail and summarizes our recent efforts to elucidate the low-temperature kinetics of trinitrotriaminobenzene (TATB) and nitroguanidine (NQ).

  12. Concentration Dependence of Afterglow Suppression in CsI:Tl,Sm

    Science.gov (United States)

    Kappers, L. A.; Bartram, R. H.; Hamilton, D. S.; Lempicki, A.; Brecher, C.; Gaysinskiy, V.; Ovechkina, E. E.; Nagarkar, V. V.

    2010-11-01

    Combined radioluminescence, afterglow and thermoluminescence experiments on single-crystal samples of co-doped CsI:Tl,Sm suggest that deeper samarium electron traps scavenge electrons from shallower thallium traps and that electrons subsequently released by samarium recombine non-radiatively with holes trapped as VKA(Tl+) centers, thus providing a mechanism for suppression of trapped-charge accumulation in repetitive applications. In the present investigation, experiments performed on two single-crystal samples of CsI:Tl,Sm with nominal concentrations of 0.11% Tl+ and of 0.2% and 0.05% Sm2+, respectively, support the inference that electrons tunnel freely between samarium ions and are trapped preferentially near VKA(Tl+) centers where non-radiative recombination is the rate-limiting step.

  13. Concentration Dependence of Afterglow Suppression in CsI:Tl,Sm

    Energy Technology Data Exchange (ETDEWEB)

    Kappers, L A; Bartram, R H; Hamilton, D S; Lempicki, A; Brecher, C; Gaysinskiy, V; Ovechkina, E E; Nagarkar, V V, E-mail: lawrence.kappers@uconn.ed

    2010-11-01

    Combined radioluminescence, afterglow and thermoluminescence experiments on single-crystal samples of co-doped CsI:Tl,Sm suggest that deeper samarium electron traps scavenge electrons from shallower thallium traps and that electrons subsequently released by samarium recombine non-radiatively with holes trapped as V{sub KA}(Tl{sup +}) centers, thus providing a mechanism for suppression of trapped-charge accumulation in repetitive applications. In the present investigation, experiments performed on two single-crystal samples of CsI:Tl,Sm with nominal concentrations of 0.11% Tl{sup +} and of 0.2% and 0.05% Sm{sup 2+}, respectively, support the inference that electrons tunnel freely between samarium ions and are trapped preferentially near V{sub KA}(Tl{sup +}) centers where non-radiative recombination is the rate-limiting step.

  14. SIMULATIONS OF GAMMA-RAY BURST JETS IN A STRATIFIED EXTERNAL MEDIUM: DYNAMICS, AFTERGLOW LIGHT CURVES, JET BREAKS, AND RADIO CALORIMETRY

    Energy Technology Data Exchange (ETDEWEB)

    De Colle, Fabio; Ramirez-Ruiz, Enrico [TASC, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Granot, Jonathan [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Lopez-Camara, Diego, E-mail: fabio@ucolick.org [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ap. 70-543, 04510 D.F. (Mexico)

    2012-05-20

    The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with {rho}{sub ext}{proportional_to}r{sup -k} for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle {theta}{sub 0} = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor {Gamma} drops below {theta}{sup -1}{sub 0}. For larger k values, however, the lateral expansion is faster at early times (when {Gamma} > {theta}{sup -1}{sub 0}) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for {theta}{sub obs} {<=} {theta}{sub 0}) than by the slope of the external density profile (for 0 {<=} k {<=} 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results

  15. Simulations of Gamma-Ray Burst Jets in a Stratified External Medium: Dynamics, Afterglow Light Curves, Jet Breaks, and Radio Calorimetry

    Science.gov (United States)

    De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego

    2012-05-01

    The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with ρextvpropr -k for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle θ0 = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor Γ drops below θ-1 0. For larger k values, however, the lateral expansion is faster at early times (when Γ > θ-1 0) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for θobs <= θ0) than by the slope of the external density profile (for 0 <= k <= 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results in a clear bump-like feature in the light curve. However, for larger k values the jet decelerates more

  16. Electromagnetic emission from long-lived binary neutron star merger remnants I: formulation of the problem

    CERN Document Server

    Siegel, Daniel M

    2015-01-01

    Binary neutron star (BNS) mergers are the leading model to explain the phenomenology of short gamma-ray bursts (SGRBs), which are among the most luminous explosions in the universe. Recent observations of long-lasting X-ray afterglows of SGRBs challenge standard paradigms and indicate that in a large fraction of events a long-lived neutron star (NS) may be formed rather than a black hole. Understanding the mechanisms underlying these afterglows is necessary in order to address the open questions concerning the nature of SGRB central engines. However, recent theoretical progress has been hampered by the fact that the timescales of interest for the afterglow emission are inaccessible to numerical relativity simulations. Here we present a detailed model to bridge the gap between numerical simulations of the merger process and the relevant timescales for the afterglows, assuming that the merger results in a long-lived NS. This model is formulated in terms of a set of coupled differential equations that follow the...

  17. GAMMA-RAY BURST DYNAMICS AND AFTERGLOW RADIATION FROM ADAPTIVE MESH REFINEMENT, SPECIAL RELATIVISTIC HYDRODYNAMIC SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    De Colle, Fabio; Ramirez-Ruiz, Enrico [Astronomy and Astrophysics Department, University of California, Santa Cruz, CA 95064 (United States); Granot, Jonathan [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Lopez-Camara, Diego, E-mail: fabio@ucolick.org [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ap. 70-543, 04510 D.F. (Mexico)

    2012-02-20

    We report on the development of Mezcal-SRHD, a new adaptive mesh refinement, special relativistic hydrodynamics (SRHD) code, developed with the aim of studying the highly relativistic flows in gamma-ray burst sources. The SRHD equations are solved using finite-volume conservative solvers, with second-order interpolation in space and time. The correct implementation of the algorithms is verified by one-dimensional (1D) and multi-dimensional tests. The code is then applied to study the propagation of 1D spherical impulsive blast waves expanding in a stratified medium with {rho}{proportional_to}r{sup -k}, bridging between the relativistic and Newtonian phases (which are described by the Blandford-McKee and Sedov-Taylor self-similar solutions, respectively), as well as to a two-dimensional (2D) cylindrically symmetric impulsive jet propagating in a constant density medium. It is shown that the deceleration to nonrelativistic speeds in one dimension occurs on scales significantly larger than the Sedov length. This transition is further delayed with respect to the Sedov length as the degree of stratification of the ambient medium is increased. This result, together with the scaling of position, Lorentz factor, and the shock velocity as a function of time and shock radius, is explained here using a simple analytical model based on energy conservation. The method used for calculating the afterglow radiation by post-processing the results of the simulations is described in detail. The light curves computed using the results of 1D numerical simulations during the relativistic stage correctly reproduce those calculated assuming the self-similar Blandford-McKee solution for the evolution of the flow. The jet dynamics from our 2D simulations and the resulting afterglow light curves, including the jet break, are in good agreement with those presented in previous works. Finally, we show how the details of the dynamics critically depend on properly resolving the structure of the

  18. Gamma-Ray Burst Dynamics and Afterglow Radiation from Adaptive Mesh Refinement, Special Relativistic Hydrodynamic Simulations

    Science.gov (United States)

    De Colle, Fabio; Granot, Jonathan; López-Cámara, Diego; Ramirez-Ruiz, Enrico

    2012-02-01

    We report on the development of Mezcal-SRHD, a new adaptive mesh refinement, special relativistic hydrodynamics (SRHD) code, developed with the aim of studying the highly relativistic flows in gamma-ray burst sources. The SRHD equations are solved using finite-volume conservative solvers, with second-order interpolation in space and time. The correct implementation of the algorithms is verified by one-dimensional (1D) and multi-dimensional tests. The code is then applied to study the propagation of 1D spherical impulsive blast waves expanding in a stratified medium with ρvpropr -k , bridging between the relativistic and Newtonian phases (which are described by the Blandford-McKee and Sedov-Taylor self-similar solutions, respectively), as well as to a two-dimensional (2D) cylindrically symmetric impulsive jet propagating in a constant density medium. It is shown that the deceleration to nonrelativistic speeds in one dimension occurs on scales significantly larger than the Sedov length. This transition is further delayed with respect to the Sedov length as the degree of stratification of the ambient medium is increased. This result, together with the scaling of position, Lorentz factor, and the shock velocity as a function of time and shock radius, is explained here using a simple analytical model based on energy conservation. The method used for calculating the afterglow radiation by post-processing the results of the simulations is described in detail. The light curves computed using the results of 1D numerical simulations during the relativistic stage correctly reproduce those calculated assuming the self-similar Blandford-McKee solution for the evolution of the flow. The jet dynamics from our 2D simulations and the resulting afterglow light curves, including the jet break, are in good agreement with those presented in previous works. Finally, we show how the details of the dynamics critically depend on properly resolving the structure of the relativistic flow.

  19. A Large Catalog of Homogeneous Ultra-Violet/Optical GRB Afterglows: Temporal and Spectral Evolution

    Science.gov (United States)

    Roming, Peter W. A.; Koch, T. Scott; Oates, Samantha R.; Porterfield, Blair L.; Bayless, Amanda J.; Breeveld, Alice A.; Gronwall, Caryl; Kuin, N. P. M.; Page, Mat J.; de Pasquale, Massimiliano; Siegel, Michael H.; Swenson, Craig A.; Tobler, Jennifer M.

    2017-02-01

    We present the second Swift Ultra-Violet/Optical Telescope (UVOT) gamma-ray burst (GRB) afterglow catalog, greatly expanding on the first Swift UVOT GRB afterglow catalog. The second catalog is constructed from a database containing over 120,000 independent UVOT observations of 538 GRBs first detected by Swift, the High Energy Transient Explorer 2 (HETE2), the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), the Interplanetary Network (IPN), Fermi, and Astro-rivelatore Gamma a Immagini Leggero (AGILE). The catalog covers GRBs discovered from 2005 January 17 to 2010 December 25. Using photometric information in three UV bands, three optical bands, and a “white” or open filter, the data are optimally coadded to maximize the number of detections and normalized to one band to provide a detailed light curve. The catalog provides positional, temporal, and photometric information for each burst, as well as Swift Burst Alert Telescope and X-ray Telescope (XRT) GRB parameters. Temporal slopes are provided for each UVOT filter. The temporal slope per filter of almost half the GRBs are fit with a single power law, but one to three breaks are required in the remaining bursts. Morphological comparisons with the X-ray reveal that ∼ 75 % of the UVOT light curves are similar to one of the four morphologies identified by Evans et al. (2009). The remaining ∼ 25 % have a newly identified morphology. For many bursts, redshift- and extinction-corrected UV/optical spectral slopes are also provided at 2 × 103, 2 × 104, and 2 × 105 s.

  20. Factors affecting afterglow properties of red-emitting phosphor MgSiO3∶Mn2+,Nd3+ for luminescent fiber

    Institute of Scientific and Technical Information of China (English)

    ZHU Yanan; GE Mingqiao

    2013-01-01

    With stable physical properties,the rare-earth silicate phosphor of MgSiO3∶Mn2+,Nd3+ is one of the suitable luminescent materials used in preparing functional fibers.In order to promote the afterglow properties of red-emitting phosphors,we prepared it by means of solid-state reaction,and the effect of manufacturing elements including H3BO3 and environmental factor of calcining temperature,type of flux on its luminescence property were investigated through evaluating their afterglow properties.The results showed that with the concentration of Nd3+ increasing,the amounts of H3BO3 doping and calcining temperature,the afterglow time and initial brightness of the rare-earth silicate phosphor increased and then decreased gradually.The afterglow properties of different flux concentration were different from one to another as:H3BO3>Na+>K+>No flux.

  1. High-energy γ-ray emission from gamma-raybursts-before GLAST

    Institute of Scientific and Technical Information of China (English)

    Yi-Zhong FAN; Tsvi PIRAN

    2008-01-01

    Gamma-ray bursts (GRBs) are short and intense emission of soft γ-rays,which have fascinated astronomers and astrophysicists since their unexpected discovery in 1960s.The X-ray/optical/radio afterglow observations confirm the cosmological origin of GRBs,support the fireball model,and imply a long-activity of the central engine.The high-energy γ-ray emission (>20 MeV) from GRBs is particularly important because they shed some lights on the radiation mechanisms and can help us to constrain the physical processes giving rise to the early afterglows. In this work,we review observational and theoretical studies of the high-energy emission from GRBs.Special attention is given to the expected high-energy emission signatures accompanying the canonical early-time X-ray afterglow that was observed by the Swift X-ray Telescope.We also discuss the detection prospect of the upcoming GLAST satellite and the current ground-based Cerenkov detectors.

  2. High Energy Gamma-Ray Emission from Gamma-Ray Bursts - Before GLAST

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Yi-Zhong; Piran, Tsvi

    2011-11-29

    Gamma-ray bursts (GRBs) are short and intense emission of soft {gamma}-rays, which have fascinated astronomers and astrophysicists since their unexpected discovery in 1960s. The X-ray/optical/radio afterglow observations confirm the cosmological origin of GRBs, support the fireball model, and imply a long-activity of the central engine. The high-energy {gamma}-ray emission (> 20 MeV) from GRBs is particularly important because they shed some lights on the radiation mechanisms and can help us to constrain the physical processes giving rise to the early afterglows. In this work, we review observational and theoretical studies of the high-energy emission from GRBs. Special attention is given to the expected high-energy emission signatures accompanying the canonical early-time X-ray afterglow that was observed by the Swift X-ray Telescope. We also discuss the detection prospect of the upcoming GLAST satellite and the current ground-based Cerenkov detectors.

  3. Intrinsic energy partition in fission

    Directory of Open Access Journals (Sweden)

    Mirea M.

    2013-03-01

    Full Text Available The intrinsic energy partition between two complementary fission fragments is investigated microscopically. The intrinsic excitation energy of fission fragments is dynamically evaluated in terms of the time-dependent pairing equations. These equations are corroborated with two conditions. One of them fixes the number of particles and the other separates the pairing active spaces associated to the two fragments in the vicinity of the scission configuration. The excitation energy in a wide distribution of fission fragments is calculated for the 234U parent nucleus.

  4. Exploring Broadband GRB Behavior During gamma-ray Emission

    CERN Document Server

    Yost, S A; Rykoff, E S; Aharonian, F; Akerlof, C W; Alday, A; Ashley, M C B; Barthelmy, S; Burrows, D; Depoy, D L; Dufour, R J; Eastman, J D; Forgey, R D; Gehrels, N; G"uver, T; Halpern, J P; Hardin, L C; Horns, D; Krimm, H A; Lepine, S; Liang, E P; Marshall, J L; McKay, T A; Mineo, T; Mirabal, N; Phillips, A; Prieto, J L; Quimby, R M; Romano, P; Rowell, G; Rujopakarn, W; Schaefer, B E; Silverman, J M; Siverd, R; Skinner, M; Smith, D A; Smith, I A; Tonnesen, S; Troja, E; Vestrand, W T; Wheeler, J C; Wren, J; Yuan, F; Zhang, B

    2006-01-01

    The robotic ROTSE-III telescope network detected prompt optical emission contemporaneous with the gamma-ray emission of Swift events GRB051109A and GRB051111. Both datasets have continuous coverage at high signal-to-noise levels from the prompt phase onwards, thus the early observations are readily compared to the Swift XRT and BAT high energy detections. In both cases, the optical afterglow is established, declining steadily during the prompt emission. For GRB051111, there is evidence of an excess optical component during the prompt emission. The component is consistent with the flux spectrally extrapolated from the gamma-rays, using the gamma-ray spectral index. A compilation of spectral information from previous prompt detections shows that such a component is unusual. The existence of two prompt optical components - one connected to the high-energy emission, the other to separate afterglow flux, as indicated in GRB051111 - is not compatible with a simple ``external-external'' shock model for the GRB and i...

  5. Low-Afterglow, High-Refractive-Index Liquid Scintillators for Fast-Neutron Spectrometry and Imaging Applications

    CERN Document Server

    Lauck, Ronald; Bromberger, Benjamin; Dangendorf, Volker; Goldberg, Mark B; Mor, Ilan; Tittelmeier, Kai; Vartsky, David

    2009-01-01

    For ion and neutron spectrometry and imaging applications at a high intensity pulsed laser facility, fast liquid scintillators with very low afterglow are required. Furthermore, neutron imaging with fiber (or liquid-core) capillary arrays calls for scintillation materials with high refractive index. To this end, we have examined various combinations of established mixtures of fluors and solvents, that were enriched alternatively with nitrogen or oxygen. Dissolved molecular oxygen is known to be a highly effective quenching agent, that efficiently suppresses the population of the triplet states in the fluor, which are primarily responsible for the afterglow. For measuring the glow curves of scintillators, we have employed the time-correlated single photon counting (TCSPC) technique, characterized by high dynamic range of several orders of magnitude in light intensity. In this paper we outline the application for the fast scintillators, briefly present the scintillation mechanism in liquids, describe our specif...

  6. Use of Interrupted Helium Flow in the Analysis of Vapor Samples with Flowing Atmospheric-Pressure Afterglow-Mass Spectrometry

    Science.gov (United States)

    Storey, Andrew P.; Zeiri, Offer M.; Ray, Steven J.; Hieftje, Gary M.

    2017-02-01

    The flowing atmospheric-pressure afterglow (FAPA) source was used for the mass-spectrometric analysis of vapor samples introduced between the source and mass spectrometer inlet. Through interrupted operation of the plasma-supporting helium flow, helium consumption is greatly reduced and dynamic gas behavior occurs that was characterized by schlieren imaging. Moreover, mass spectra acquired immediately after the onset of helium flow exhibit a signal spike before declining and ultimately reaching a steady level. This initial signal appears to be due to greater interaction of sample vapor with the afterglow of the source when helium flow resumes. In part, the initial spike in signal can be attributed to a pooling of analyte vapor in the absence of helium flow from the source. Time-resolved schlieren imaging of the helium flow during on and off cycles provided insight into gas-flow patterns between the FAPA source and the MS inlet that were correlated with mass-spectral data.

  7. Shallow Decay Phase of the Early X-Ray Afterglow from External Shock in a Wind Environment

    Institute of Scientific and Technical Information of China (English)

    雷海东; 汪九洲; 吕静; 邹远川

    2011-01-01

    We investigate the shallow decay phase of an early x-ray afterglow in gamma-ray bursts discovered by Swift, and suggest that both the shallow decay phase and the normal phase are from external shock in a wind environment, while the transferring time is the deceleration time. We apply this model to GRBs 050319 and 081008, and find that they can be explained by choosing a proper set of parameters.%We investigate the shallow decay phase of an early x-ray afterglow in gamma-ray bursts discovered by Swift,and suggest that both the shallow decay phase and the normal phase are from external shock in a wind environment,while the transferring time is the deceleration time.We apply this model to GRBs 050319 and 081008,and find that they can be explained by choosing a proper set of parameters.

  8. Variation of microphysics in wind bubbles: an alternative mechanism for explaining the rebrightenings in Gamma-ray burst afterglows

    Science.gov (United States)

    Kong, S. W.; Wong, A. Y. L.; Huang, Y. F.; Cheng, K. S.

    2010-02-01

    Conventionally, long Gamma-ray bursts (GRBs) are thought to be caused by the core collapses of massive stars. During the lifetime of a massive star, a stellar wind bubble environment should be produced. Furthermore, the microphysics shock parameters may vary along with the evolution of the fireball. Here, we investigate the variation of the microphysics shock parameters under the condition of wind bubble environment, and allow the microphysics shock parameters to be discontinuous at shocks in the ambient medium. It is found that our model can acceptably reproduce the rebrightenings observed in GRB afterglows, at least in some cases. The effects of various model parameters on rebrightenings are investigated. The rebrightenings observed in both the R-band and X-ray afterglow light curves of GRB 060206, GRB 070311 and GRB 071010A are reproduced in this model.

  9. Intrinsic Motivation in Physical Education

    Science.gov (United States)

    Davies, Benjamin; Nambiar, Nathan; Hemphill, Caroline; Devietti, Elizabeth; Massengale, Alexandra; McCredie, Patrick

    2015-01-01

    This article describes ways in which educators can use Harter's perceived competence motivation theory, the achievement goal theory, and self-determination theory to develop students' intrinsic motivation to maintain physical fitness, as demonstrated by the Sound Body Sound Mind curriculum and proven effective by the 2013 University of…

  10. Luminescent Afterglow Behavior in the M2Si5N8: Eu Family (M = Ca, Sr, Ba

    Directory of Open Access Journals (Sweden)

    Koen Van den Eeckhout

    2011-05-01

    Full Text Available Persistent luminescent materials are able to emit light for hours after being excited. The majority of persistent phosphors emit in the blue or green region of the visible spectrum. Orange- or red-emitting phosphors, strongly desired for emergency signage and medical imaging, are scarce. We prepared the nitrido-silicates Ca2Si5N8:Eu (orange, Sr2Si5N8:Eu (reddish, Ba2Si5N8:Eu (yellowish orange, and their rare-earth codoped variants (R = Nd, Dy, Sm, Tm through a solid state reaction, and investigated their luminescence and afterglow properties. In this paper, we describe how the persistent luminescence is affected by the type of codopant and the choice and ratio of the starting products. All the materials exhibit some form of persistent luminescence, but for Sr2Si5N8:Eu,R this is very weak. In Ba2Si5N8:Eu the afterglow remains visible for about 400 s, and Ca2Si5N8:Eu,Tm shows the brightest and longest afterglow, lasting about 2,500 s. For optimal persistent luminescence, the dopant and codopant should be added in their fluoride form, in concentrations below 1 mol%. A Ca3N2 deficiency of about 5% triples the afterglow intensity. Our results show that Ba2Si5N8:Eu(,R and Ca2Si5N8:Eu(,R are promising persistent phosphors for applications requiring orange or red light.

  11. A two-step energy injection explanation for the rebrightenings of the multi-band afterglow of GRB 081029

    Institute of Scientific and Technical Information of China (English)

    Yong-Bo Yu; Yong-Feng Huang

    2013-01-01

    The afterglow of GRB 081029 showed unusual behavior,with a significant rebrightening being observed at the optical wavelength at about 3000 s after the burst.One possible explanation is that the rebrightening resulted from an energy injection.Here we present a detailed numerical study of the energy injection process and interpret the X-ray and optical afterglow light curves of GRB 081029.In our model,we have assumed two periods of energy injection,each with a constant injection power.One injection starts at 2.8 × 103 s and lasts for about 2500 s,with a power of 7.0 × 1047 erg s-1.This energy injection mainly accounts for the rapid rebrightening at about 3000 s.The other injection starts at 8.0 × 103 s and lasts for about 5000 s.The injection power is 3.5 × 1047 erg s-1.This energy injection can help to explain the slight rebrightening at about 10 000 s.It is shown that the observed optical afterglow,especially the marked rebrightening at about 3000 s,can be reproduced well.In the X-ray band,the predicted amplitude of the rebrightening is much shallower,which is also consistent with the observed X-ray afterglow light curve.It is argued that the two periods of energy injection can be produced by clumpy materials falling onto the central compact object of the burster,which leads to an enhancement of accretion and gives rise to a strong temporary outflow.

  12. Extinction of gamma-ray burst afterglows as a diagnostic of the location of cosmic star formation

    CERN Document Server

    Ramirez-Ruiz, E; Blain, A W; Ramirez-Ruiz, Enrico; Trentham, Neil

    2002-01-01

    The properties of gamma-ray bursts (GRBs) and their afterglows are used to investigate the location of star formation activity through the history of the Universe. This approach is motivated by the following: (i) GRBs are thought to be associated with the deaths of massive stars and so the GRB rate ought to follow the massive star formation rate, (ii) GRBs are the final evolutionary phase of these short-lived stars, which do not travel far from their birthplace, and so should be located where the stars formed, and (iii) The differential effects of dust extinction on GRB afterglows between the X-ray and optical wavebands can reveal whether or not large amounts of gas and dust are present in GRB host galaxies. From recent evidence, we estimate that a significant fraction (about 75%) of stars in the Universe formed in galaxies that are brightest at rest-frame far-infrared (IR) wavelengths. This value is marginally consistent with observations: 60 +/- 15% of GRBs have no detected optical afterglow, whereas almost...

  13. Investigation of the Afterglow Mode with the Caprice ECRIS for the GSI Heavy-Ion-Synchrotron operation

    CERN Document Server

    Tinschert, K; Lang, R; Schulte, H; Spädtke, P

    1999-01-01

    The Caprice-type ECRIS of the High Charge State Injector (HLI) of GSI predominantly has been operated in DC mode so far to deliver high duty cycle beams for the experimental area of the LINAC (UNILAC). The increasing demand of the Heavy Ion Synchrotron (SIS) for high intensities of heavy ion beams at very low duty cycle favours the application of the afterglow mode by pulsed operation of the ECRIS in these cases. Experiments with O, Ar, Xe and mainly with Pb were performed at the new ECR injector setup (EIS) which is a copy of the HLI injection beam line. Different RF pulse lengths and repetition rates were compared to optimise the respective afterglow intensities. For Pb two different types of ovens were investigated and modifications of the extraction system were applied. Thus peak intensities in the afterglow for 208Pb27+ of up to 200 emA could be obtained. Stable operation for time periods of several days could be achieved at reduced intensity level. Operational experiences are reported under the aspect o...

  14. iPTF14yb: The First Discovery of a GRB Afterglow Independent of a High-Energy Trigger

    CERN Document Server

    Cenko, S Bradley; Perley, Daniel A; Horesh, Assaf; Corsi, Alessandra; Fox, Derek B; Cao, Yi; Kasliwal, Mansi M; Lien, Amy; Arcavi, Iair; Bloom, Joshua S; Butler, Nat R; Cucchiara, Antonino; de Diego, Jose A; Filippenko, Alexei V; Gal-Yam, Avishay; Gehrels, Neil; Georgiev, Leonid; Gonzalez, J Jesus; Graham, John F; Greiner, Jochen; Kann, D Alexander; Klein, Christopher R; Knust, Fabian; Kulkarni, S R; Kutyrev, Alexander; Laher, Russ; Lee, William H; Nugent, Peter E; Prochaska, J Xavier; Ramirez-Ruiz, Enrico; Richer, Michael G; Rubin, Adam; Urata, Yuji; Varela, Karla; Watson, Alan M; Wozniak, Przemek R

    2015-01-01

    We report here the discovery by the Intermediate Palomar Transient Factory (iPTF) of iPTF14yb, a luminous ($M_{r}\\approx-27.8$ mag), cosmological (redshift 1.9733), rapidly fading optical transient. We demonstrate, based on probabilistic arguments and a comparison with the broader population, that iPTF14yb is the optical afterglow of the long-duration gamma-ray burst GRB 140226A. This marks the first unambiguous discovery of a GRB afterglow prior to (and thus entirely independent of) an associated high-energy trigger. We estimate the rate of iPTF14yb-like sources (i.e., cosmologically distant relativistic explosions) based on iPTF observations, inferring an all-sky value of $\\Re_{\\mathrm{rel}}=610$ yr$^{-1}$ (68% confidence interval of 110-2000 yr$^{-1}$). Our derived rate is consistent (within the large uncertainty) with the all-sky rate of on-axis GRBs derived by the Swift satellite. Finally, we briefly discuss the implications of the nondetection to date of bona fide "orphan" afterglows (i.e., those lackin...

  15. VLT identification of the optical afterglow of the gamma-ray burst GRB000131 at z=4.50

    DEFF Research Database (Denmark)

    Andersen, M.I.; Hjorth, J.; Jesen, B.L.

    2000-01-01

    Angstrom. This places GRB 000131 at a redshift of 4.500 +/- 0.015. The inferred isotropic energy release in gamma rays alone was similar to 10(54) erg (depending on the assumed cosmology). The rapid power-law decay of the afterglow (index alpha = 2.25, similar to bursts with a prior break in the lightcurve......We report the discovery of the gamma-ray burst GRB 000131 and its optical afterglow. The optical identification was made with the VLT 84 hours after the burst following a BATSE detection and an Inter Planetary Network localization. GRB 000131 was a bright, long-duration GRB, with an apparent...... precursor signal 62 s prior to trigger. The afterglow was detected in ESO VLT, NTT, and DK1.54m follow-up observations. Broad-band and spectroscopic observations of the spectral energy distribution reveals a sharp break at optical wavelengths which is interpreted as a Ly alpha absorption edge at 6700...

  16. VLT identification of the optical afterglow of the gamma-ray burst GRB 000131 at z=4.50

    DEFF Research Database (Denmark)

    Andersen, M.I.; Hjorth, J.; Pedersen, H.

    2000-01-01

    Angstrom. This places GRB 000131 at a redshift of 4.500 +/- 0.015. The inferred isotropic energy release in gamma rays alone was similar to 10(54) erg (depending on the assumed cosmology). The rapid power-law decay of the afterglow (index alpha = 2.25, similar to bursts with a prior break in the lightcurve......We report the discovery of the gamma-ray burst GRB 000131 and its optical afterglow. The optical identification was made with the VLT 84 hours after the burst following a BATSE detection and an Inter Planetary Network localization. GRB 000131 was a bright, long-duration GRB, with an apparent...... precursor signal 62 s prior to trigger. The afterglow was detected in ESO VLT, NTT, and DK1.54m follow-up observations. Broad-band and spectroscopic observations of the spectral energy distribution reveals a sharp break at optical wavelengths which is interpreted as a Ly alpha absorption edge at 6700...

  17. Imprints of Electron-positron Winds on the Multi-wavelength Afterglows of Gamma-ray Bursts

    CERN Document Server

    Geng, J J; Huang, Y F; Li, L; Dai, Z G

    2016-01-01

    Optical re-brightenings in the afterglows of some gamma-ray bursts (GRBs) are unexpected within the framework of the simple external shock model. While it has been suggested that the central engines of some GRBs are newly born magnetars, we aim to relate the behaviors of magnetars to the optical re-brightenings. A newly born magnetar will lose its rotational energy in the form of Poynting-flux, which may be converted into a wind of electron-positron pairs through some magnetic dissipation processes. As proposed by Dai (2004), this wind will catch up with the GRB outflow and a long-lasting reverse shock would form. By applying this scenario to GRB afterglows, we find that the reverse shock propagating back into the electron-positron wind can lead to an observable optical re-brightening and a simultaneous X-ray plateau (or X-ray shallow decay). In our study, we select four GRBs, i.e., GRB 080413B, GRB 090426, GRB 091029, and GRB 100814A, of which the optical afterglows are well observed and show clear re-bright...

  18. VLT identification of the optical afterglow of the gamma-ray burst GRB 000131 at z=4.50

    DEFF Research Database (Denmark)

    Andersen, M.I.; Hjorth, J.; Pedersen, H.

    2000-01-01

    Angstrom. This places GRB 000131 at a redshift of 4.500 +/- 0.015. The inferred isotropic energy release in gamma rays alone was similar to 10(54) erg (depending on the assumed cosmology). The rapid power-law decay of the afterglow (index alpha = 2.25, similar to bursts with a prior break in the lightcurve......We report the discovery of the gamma-ray burst GRB 000131 and its optical afterglow. The optical identification was made with the VLT 84 hours after the burst following a BATSE detection and an Inter Planetary Network localization. GRB 000131 was a bright, long-duration GRB, with an apparent...... precursor signal 62 s prior to trigger. The afterglow was detected in ESO VLT, NTT, and DK1.54m follow-up observations. Broad-band and spectroscopic observations of the spectral energy distribution reveals a sharp break at optical wavelengths which is interpreted as a Ly alpha absorption edge at 6700...

  19. VLT identification of the optical afterglow of the gamma-ray burst GRB000131 at z=4.50

    DEFF Research Database (Denmark)

    Andersen, M.I.; Hjorth, J.; Jesen, B.L.

    2000-01-01

    Angstrom. This places GRB 000131 at a redshift of 4.500 +/- 0.015. The inferred isotropic energy release in gamma rays alone was similar to 10(54) erg (depending on the assumed cosmology). The rapid power-law decay of the afterglow (index alpha = 2.25, similar to bursts with a prior break in the lightcurve......We report the discovery of the gamma-ray burst GRB 000131 and its optical afterglow. The optical identification was made with the VLT 84 hours after the burst following a BATSE detection and an Inter Planetary Network localization. GRB 000131 was a bright, long-duration GRB, with an apparent...... precursor signal 62 s prior to trigger. The afterglow was detected in ESO VLT, NTT, and DK1.54m follow-up observations. Broad-band and spectroscopic observations of the spectral energy distribution reveals a sharp break at optical wavelengths which is interpreted as a Ly alpha absorption edge at 6700...

  20. VLT identification of the optical afterglow of the gamma-ray burst GRB 000131 at z=4.50

    DEFF Research Database (Denmark)

    Andersen, M. I.; Hjorth, J.; Pedersen, H.

    2000-01-01

    . This places GRB 000131 at a redshift of 4.500 +/- 0.015. The inferred isotropic energy release in gamma rays alone was approximately 10^54 erg (depending on the assumed cosmology). The rapid power-law decay of the afterglow (index alpha=2.25, similar to bursts with a prior break in the lightcurve), however......We report the discovery of the gamma-ray burst GRB 000131 and its optical afterglow. The optical identification was made with the VLT 84 hours after the burst following a BATSE detection and an Inter Planetary Network localization. GRB 000131 was a bright, long-duration GRB, with an apparent...... precursor signal 62 s prior to trigger. The afterglow was detected in ESO VLT, NTT, and DK1.54m follow-up observations. Broad-band and spectroscopic observations of the spectral energy distribution reveals a sharp break at optical wavelengths which is interpreted as a Ly-alpha absorption edge at 6700 A...

  1. The Needle in the 100 deg2 Haystack: Uncovering Afterglows of Fermi GRBs with the Palomar Transient Factory

    CERN Document Server

    Singer, Leo P; Cenko, S Bradley; Perley, Daniel A; Anderson, Gemma E; Anupama, G C; Arcavi, Iair; Bhalerao, Varun; Bue, Brian D; Cao, Yi; Connaughton, Valerie; Corsi, Alessandra; Cucchiara, Antonino; Fender, Rob P; Fox, Derek B; Gehrels, Neil; Goldstein, Adam; Gorosabel, J; Horesh, Assaf; Hurley, Kevin; Johansson, Joel; Kann, D A; Kouveliotou, Chryssa; Huang, Kuiyun; Kulkarni, S R; Masci, Frank; Nugent, Peter; Rau, Arne; Rebbapragada, Umaa D; Staley, Tim D; Svinkin, Dmitry; Thöne, C C; Postigo, A de Ugarte; Urata, Yuji; Weinstein, Alan

    2015-01-01

    The Fermi Gamma-Ray Space Telescope has greatly expanded the number and energy window of observations of gamma-ray bursts (GRBs). However, the coarse localizations of tens to a hundred square degrees provided by the Fermi Gamma-ray Burst Monitor (GBM) instrument have posed a formidable obstacle to locating the bursts' host galaxies, measuring their redshifts, and tracking their panchromatic afterglows. We have built a target of opportunity mode for the intermediate Palomar Transient Factory (iPTF) in order to perform targeted searches for Fermi afterglows. Here, we present the results of one year of this program: eight afterglow discoveries, two of which (GRBs 130702A and 140606B) were at low redshift (z=0.145 and 0.384 respectively) and had spectroscopically confirmed broad-line type Ic supernovae. We present our broadband follow-up including spectroscopy as well as X-ray, UV, optical, millimeter, and radio observations. We study possible selection effects in the context of the total Fermi and Swift GRB samp...

  2. Very Bright Prompt and Reverse Shock Emission of GRB 140512A

    CERN Document Server

    Huang, Xiao-Li; Yi, Shuang-Xi; Zhong, Shu-Qing; Qiu, Yu-Lei; Deng, Jin-Song; Wei, Jian-Yan; Liang, En-Wei

    2016-01-01

    We report our observations of very bright prompt optical and reverse shock (RS) optical emission of GRB 140512A and analyze its multi-wavelength data observed with the {\\em Swift} and {\\em Fermi} missions. It is found that the joint optical-X-ray-gamma-ray spectrum with our first optical detection (R=13.09 mag) at $T_0+136$ seconds during the second episode of the prompt gamma-rays can be fit by a single power-law with index $-1.32\\pm 0.01$. Our empirical fit to the afterglow lightcurves indicates that the observed bright optical afterglow with R=13.00 mag at the peak time is consistent with predictions of the RS and forward shock (FS) emission of external shock models. Joint optical-X-ray afterglow spectrum is well fit with an absorbed single power-law, with an index evolving with time from $-1.86\\pm 0.01$ at the peak time to $-1.57\\pm 0.01$ at late epoch, which could be due to the evolution of the ratio of the RS to FS emission fluxes. We fit the lightcurves with standard external models, and derive the phy...

  3. Harmonic structures and intrinsic torsion

    DEFF Research Database (Denmark)

    Conti, Diego; Madsen, Thomas Bruun

    We discuss the construction of 8-manifolds with harmonic Sp(2)Sp(1)-structures. In particular, we find 10 new examples of nilmanifolds that admit a closed 4-form Omega whose stabiliser is Sp(2)Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We present a thorough inv...... investigation of the intrinsic torsion of such structures; in addition to the construction of harmonic structures, this analysis leads to explicit Lie group examples with invariant intrinsic torsion.......We discuss the construction of 8-manifolds with harmonic Sp(2)Sp(1)-structures. In particular, we find 10 new examples of nilmanifolds that admit a closed 4-form Omega whose stabiliser is Sp(2)Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We present a thorough...

  4. Harmonic structures and intrinsic torsion

    DEFF Research Database (Denmark)

    Conti, Diego; Madsen, Thomas Bruun

    2015-01-01

    We discuss the construction of Sp(2)Sp(1)-structures whose fundamental form is closed. In particular, we find 10 new examples of 8-dimensional nilmanifolds that admit an invariant closed 4-form with stabiliser Sp(2) Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We...... present a thorough investigation of the intrinsic torsion of such structures, leading to the construction of explicit Lie group examples with invariant intrinsic torsion.......We discuss the construction of Sp(2)Sp(1)-structures whose fundamental form is closed. In particular, we find 10 new examples of 8-dimensional nilmanifolds that admit an invariant closed 4-form with stabiliser Sp(2) Sp(1). Our constructions entail the notion of SO(4)-structures on 7-manifolds. We...

  5. Electromagnetic Emission from Long-lived Binary Neutron Star Merger Remnants. I. Formulation of the Problem

    Science.gov (United States)

    Siegel, Daniel M.; Ciolfi, Riccardo

    2016-03-01

    Binary neutron star (BNS) mergers are the leading model to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations of long-lasting X-ray afterglows of SGRBs challenge standard paradigms and indicate that in a large fraction of events a long-lived neutron star (NS) may be formed rather than a black hole. Understanding the mechanisms underlying these afterglows is necessary in order to address the open questions concerning the nature of SGRB central engines. However, recent theoretical progress has been hampered by the fact that the timescales of interest for the afterglow emission are inaccessible to numerical relativity simulations. Here we present a detailed model to bridge the gap between numerical simulations of the merger process and the relevant timescales for the afterglows, assuming that the merger results in a long-lived NS. This model is formulated in terms of a set of coupled differential equations that follow the evolution of the post-merger system and predict its electromagnetic (EM) emission in a self-consistent way, starting from initial data that can be extracted from BNS merger simulations. The model presented here also allows us to search for suitable EM counterparts for multimessenger astronomy, which is expected to become reality within the next few years thanks to ground-based GW detectors such as advanced LIGO and Virgo. This paper discusses the formulation and implementation of the model. In a companion paper, we employ this model to predict the EM emission from ∼ {10}-2 to ∼ {10}7 {{s}} after a BNS merger and discuss the implications in the context of SGRBs and multimessenger astronomy.

  6. X-ray Spectral Components in the Afterglow of GRB 130925A

    CERN Document Server

    Bellm, Eric C; Bhalerao, Varun; Boggs, Steven E; Cenko, S Bradley; Christensen, Finn E; Craig, William W; Forster, Karl; Fryer, Chris L; Hailey, Charles J; Harrison, Fiona A; Horesh, Assaf; Kouveliotou, Chryssa; Madsen, Kristin K; Miller, Jon M; Ofek, Eran O; Perley, Daniel A; Rana, Vikram R; Reynolds, Stephen P; Stern, Daniel; Tomsick, John A; Zhang, William W

    2014-01-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift-XRT, and Chandra. A spectral component in addition to an absorbed power-law is required at $>4\\sigma$ significance, and its spectral shape varies between two observation epochs at $2\\times10^5$ and $10^6$ seconds after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several keV width improves the fit, but it is poorly constrained in the second epoch. An additive black body or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant ($10^8$ cm), while the second powerlaw component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi-LAT.

  7. X-RAY SPECTRAL COMPONENTS OBSERVED IN THE AFTERGLOW OF GRB 130925A

    Energy Technology Data Exchange (ETDEWEB)

    Bellm, Eric C.; Forster, Karl; Harrison, Fiona A.; Madsen, Kristin K.; Perley, Daniel A.; Rana, Vikram R. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Barrière, Nicolas M.; Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Bhalerao, Varun [Inter-University Center for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007 (India); Cenko, S. Bradley [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Christensen, Finn E. [DTU Space—National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Fryer, Chris L. [CCS-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Horesh, Assaf; Ofek, Eran O. [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel); Kouveliotou, Chryssa [Astrophysics Office/ZP12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Miller, Jon M. [Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Reynolds, Stephen P. [Physics Department, NC State University, Raleigh, NC 27695 (United States); Stern, Daniel, E-mail: ebellm@caltech.edu [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); and others

    2014-04-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at >4σ significance, and its spectral shape varies between two observation epochs at 2 × 10{sup 5} and 10{sup 6} s after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several keV width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10{sup 8} cm), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.

  8. X-Ray Spectral Components Observed in the Afterglow of GRB 130925A

    Science.gov (United States)

    Bellm, Eric C.; Barriere, Nicolas M.; Bhalerao, Varun; Boggs, Steven E.; Cenko, S. Bradley; Christensen, Finn E.; Craig, William W.; Forster, Karl; Fryer, Chris L.; Hailey, Charles J.; Harrison, Fiona A.; Horesh, Assaf; Kouveliotou, Chryssa; Madsen, Kristin K.; Miller, Jon M.; Ofek, Eran O.; Perley, Daniel A.; Rana, Vikram R.; Miller, Jon M.; Stern, Daniel; Tomsick, John A.; Zhang, William W.

    2014-01-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at greater than 4 less than 1 significance, and its spectral shape varies between two observation epochs at 2 x 10 (sup 5) and 10 (sup 6) seconds after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several kiloelectronvolts width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10 (sup 8) centimeters), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.

  9. Plasma decay in the afterglow of a high-voltage nanosecond discharge in air

    Science.gov (United States)

    Aleksandrov, N. L.; Anokhin, E. M.; Kindysheva, S. V.; Kirpichnikov, A. A.; Kosarev, I. N.; Nudnova, M. M.; Starikovskaya, S. M.; Starikovskii, A. Yu.

    2012-02-01

    The decay of air plasma produced by a high-voltage nanosecond discharge at room temperature and gas pressures in the range of 1-10 Torr was studied experimentally and theoretically. The time dependence of the electron density was measured with a microwave interferometer. The initial electron density was about 1012 cm-3. The discharge homogeneity was monitored using optical methods. The dynamics of the charged particle densities in the discharge afterglow was simulated by numerically solving the balance equations for electron and ions and the equation for the electron temperature. It was shown that, under these experimental conditions, plasma electrons are mainly lost due to dissociative and three-body recombination with ions. Agreement between the measured and calculated electron densities was achieved only when the rate constant of the three-body electron-ion recombination was increased by one order of magnitude and the temperature dependence of this rate constant was modified. This indicates that the mechanism for three-body recombination of molecular ions differs from that of the well-studied mechanism of atomic ion recombination.

  10. Plasma decay in the afterglow of a high-voltage nanosecond discharge in air

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrov, N. L.; Anokhin, E. M.; Kindysheva, S. V.; Kirpichnikov, A. A.; Kosarev, I. N.; Nudnova, M. M. [Moscow Institute of Physics and Technology (Russian Federation); Starikovskaya, S. M. [Ecole Polytechnique, route de Saclay (France); Starikovskii, A. Yu. [Princeton University (United States)

    2012-02-15

    The decay of air plasma produced by a high-voltage nanosecond discharge at room temperature and gas pressures in the range of 1-10 Torr was studied experimentally and theoretically. The time dependence of the electron density was measured with a microwave interferometer. The initial electron density was about 10{sup 12} cm{sup -3}. The discharge homogeneity was monitored using optical methods. The dynamics of the charged particle densities in the discharge afterglow was simulated by numerically solving the balance equations for electron and ions and the equation for the electron temperature. It was shown that, under these experimental conditions, plasma electrons are mainly lost due to dissociative and three-body recombination with ions. Agreement between the measured and calculated electron densities was achieved only when the rate constant of the three-body electron-ion recombination was increased by one order of magnitude and the temperature dependence of this rate constant was modified. This indicates that the mechanism for three-body recombination of molecular ions differs from that of the well-studied mechanism of atomic ion recombination.

  11. Detection of the optical afterglow of GRB 000630: Implications for dark bursts

    DEFF Research Database (Denmark)

    Fynbo, J.U.; Jensen, B.L.; Gorosabel, J.

    2001-01-01

    We present the discovery of the optical transient of the long-duration gamma-ray burst GRB 000630. The optical transient was detected with the Nordic Optical Telescope 21.1 hours after the burst. At the time of discovery the magnitude of the transient was R = 23.04 +/- 0.08. The transient displayed...... a power-law decline characterized by a decay slope of alpha = -1.035 +/- 0.097. A deep image obtained 25 days after the burst shows no indication of a contribution from a supernova or a host galaxy at the position of the transient. The closest detected galaxy is a R = 324.68 +/- 0.15 galaxy 2.0 arcsec...... that i) based on the gamma-ray: properties of the current sample we cannot conclude that GRBs with no detected OTs belong to another class of GRBs than GRBs with detected OTs and ii) the majority (greater than or similar to 75%) of GRBs for which searches for optical afterglow have been unsuccessful...

  12. Multi-color Shallow Decay and Chromatic Breaks in the GRB 050319 Optical Afterglow

    CERN Document Server

    Huang, K Y; Kuo, P H; Ip, W H; Ioka, K; Aoki, T; Chen, C W; Chen, W P; Isogai, M; Lin, H C; Makishima, K; Mito, H; Miyata, T; Nakada, Y; Nishiura, S; Onda, K; Qiu, Y; Soyano, T; Tamagawa, T; Tarusawa, K; Tashiro, M; Yoshioka, T

    2006-01-01

    Multi-wavelength B, V, R, I observations of the optical afterglow of GRB 050319 were performed by the 1.05-m telescope at Kiso Observatory and the 1.0-m telescope at Lulin Observatory from 1.31 hours to 9.92 hours after the burst. Our R band lightcurves, combined with other published data, can be described by the smooth broken power-law function, with $\\alpha_1$ = -0.84 $\\pm$0.02 to $\\alpha_2$ = -0.48$\\pm$0.03, 0.04 days after the GRB. The optical lightcurves are characterized by shallow decays-- as was also observed in the X-rays-- which may have a similar origin, related to energy injection. However, our observations indicate that there is still a puzzle concerning the chromatic breaks in the R band lightcurve (at 0.04 days) and the X-ray lightcurve (at 0.004 days) that remains to be solved.

  13. GRB 991216 Joins the Jet Set Discovery and Monitoring of its Optical Afterglow

    CERN Document Server

    Halpern, J P; Mirabal, N; Kassin, S; Thorstensen, J R; Keel, W C; Diercks, A H; Bloom, J S; Harrison, F; Mattox, J R; Eracleous, M

    2000-01-01

    The optical light curve of the energetic gamma-ray burst GRB 991216 is consistent with jet-like behavior in which a power-law decay steepens from t**(-1.22 +/- 0.04) at early times to t**(-1.53 +/- 0.05) in a gradual transition at around 2 d. The derivation of the late-time decay slope takes into account the constant contribution of a host or intervening galaxy which was measured 110 d after the event at R = 24.56 +/- 0.14, although the light curve deviates from a single power law whether or not a constant term is included. The early-time spectral energy distribution of the afterglow can be described as F_nu ~ nu**(-0.74 +/- 0.05) or flatter between optical and X-ray, which, together with the slow initial decay, is characteristic of standard adiabatic evolution in a uniformly dense medium. Assuming that a reported absorption-line redshift of 1.02 is correct, the apparent isotropic energy of 6.7 x 10**53 erg is reduced by a factor of ~ 200 in the jet model, and the initial half-opening angle is ~ 6 deg. GRB 99...

  14. Afterglow Light Curves from Jetted Gamma-ray Burst Ejecta in Stellar Winds

    CERN Document Server

    Wu, X F; Huang, Y F; Ma, H T

    2003-01-01

    We revisit optical and radio afterglows arising from the shocks by relativistic conical ejecta running into pre-burst massive stellar winds. Under the homogeneous thin-shell approximation and the realistic treatment for lateral expansion of jets, our results show that a notable break of optical light curve within one decade in time indeed exists in most cases of our calculations by varying physical parameters within reasonable ranges. We rectify the conclusions of previous works on the jet+wind model, which claimed that there was no sharp break as the transition time lasts for two decades. Even for a relatively tenuous wind which cannot decelerate the relativistic jet to cause a sharp break within days, the wind termination shock due to the ram pressure balance by surrounding medium occurs at a small radius, i.e. several times $10^{17}$ cm. The jet will pass through the wind environment within several hours and run into the outer uniform dense medium. The resulting optical light curve flattens with a shallowe...

  15. Intrinsic Patterns of Human Activity

    Science.gov (United States)

    Hu, Kun; Ivanov, Plamen Ch.; Chen, Zhi; Hilton, Michael; Stanley, H. Eugene; Shea, Steven

    2003-03-01

    Activity is one of the defining features of life. Control of human activity is complex, being influenced by many factors both extrinsic and intrinsic to the body. The most obvious extrinsic factors that affect activity are the daily schedule of planned events, such as work and recreation, as well as reactions to unforeseen or random events. These extrinsic factors may account for the apparently random fluctuations in human motion observed over short time scales. The most obvious intrinsic factors are the body clocks including the circadian pacemaker that influences our sleep/wake cycle and ultradian oscillators with shorter time scales [2, 3]. These intrinsic rhythms may account for the underlying regularity in average activity level over longer periods of up to 24 h. Here we ask if the known extrinsic and intrinsic factors fully account for all complex features observed in recordings of human activity. To this end, we measure activity over two weeks from forearm motion in subjects undergoing their regular daily routine. Utilizing concepts from statistical physics, we demonstrate that during wakefulness human activity possesses previously unrecognized complex dynamic patterns. These patterns of activity are characterized by robust fractal and nonlinear dynamics including a universal probability distribution and long-range power-law correlations that are stable over a wide range of time scales (from minutes to hours). Surprisingly, we find that these dynamic patterns are unaffected by changes in the average activity level that occur within individual subjects throughout the day and on different days of the week, and between subjects. Moreover, we find that these patterns persist when the same subjects undergo time-isolation laboratory experiments designed to account for the phase of the circadian pacemaker, and control the known extrinsic factors by restricting behaviors and manipulating scheduled events including the sleep/wake cycle. We attribute these newly

  16. Systematic comparison of saturation effects and afterglow properties of Sr4Al14O25:Eu, Dy phosphor excited by alpha and beta ionizing sources and UV light

    Science.gov (United States)

    Havasi, Viktor; Tátrai, Dávid; Szabó, Gábor; Sipos, György; Kónya, Zoltán; Kukovecz, Ákos

    2017-07-01

    This study reports on the radioactive- and photo-charging effects related afterglow properties of the long-afterglow Sr4Al14O25:Eu, Dy phosphor (SAED). Saturation and oversaturation behavior, trapping and de-trapping sequences, decay profiles and resistivity of SAED to alpha, beta and UV excitations are detailed. Thermoluminescence and afterglow measurements were performed on SAED subjected to different irradiation dose/time. In order to determine the saturation point of SAED, phosphors were charged by 0.5-800 Gy dose using radioactive alpha and beta sources and for 0.02-900 min by near UV light. By radioactive excitations only a saturation tendency was observed, whereas clear indication of oversaturation was found for photo-charging. Different saturation tendencies were also observed as a function of average SAED particle size due to the different penetration depth and efficiency of the excitation radiations. A uniform de-trapping sequence, but an opposite trapping sequence was found for ionizing radiation and for UV charging due to secondary excitation effects of high-energy irradiation. After the saturation point, a slight reduction of charge carrier concentration and PL intensity were observed. This was evidenced by the shifting dominant components of the modeled afterglow and TL curves. Repeated charging by ionizing radiation does not effected the afterglow properties of SAED adversely. On the other hand, thermal exposure up to 350 °C reduced photoluminescence intensity even in inert atmosphere.

  17. Job assignments, intrinsic motivation and explicit incentives

    OpenAIRE

    Nafziger, Julia

    2008-01-01

    This paper considers the interplay of job assignments with the intrinsic and extrinsic motivation of an agent. Job assignments influence the self confidence of the agent, and thereby his intrinsic motivation. Monetary reward allow the principal to complement intrinsic motivation with extrinsic incentives. The main result is that the principal chooses an inefficient job assignment rule to enhance the agent's intrinsic motivation even though she can motivate him with monetary rewards. This show...

  18. Stochastic Intrinsic Kriging for Simulation Metamodelling

    NARCIS (Netherlands)

    Mehdad, E.; Kleijnen, Jack P.C.

    2014-01-01

    We derive intrinsic Kriging, using Matherons intrinsic random functions which eliminate the trend in classic Kriging. We formulate this intrinsic Kriging as a metamodel in deterministic and random simulation models. For random simulation we derive an experimental design that also specifies the numbe

  19. Intrinsic fluorescence of protein in turbid media using empirical relation based on Monte Carlo lookup table

    Science.gov (United States)

    Einstein, Gnanatheepam; Udayakumar, Kanniyappan; Aruna, Prakasarao; Ganesan, Singaravelu

    2017-03-01

    Fluorescence of Protein has been widely used in diagnostic oncology for characterizing cellular metabolism. However, the intensity of fluorescence emission is affected due to the absorbers and scatterers in tissue, which may lead to error in estimating exact protein content in tissue. Extraction of intrinsic fluorescence from measured fluorescence has been achieved by different methods. Among them, Monte Carlo based method yields the highest accuracy for extracting intrinsic fluorescence. In this work, we have attempted to generate a lookup table for Monte Carlo simulation of fluorescence emission by protein. Furthermore, we fitted the generated lookup table using an empirical relation. The empirical relation between measured and intrinsic fluorescence is validated using tissue phantom experiments. The proposed relation can be used for estimating intrinsic fluorescence of protein for real-time diagnostic applications and thereby improving the clinical interpretation of fluorescence spectroscopic data.

  20. Giant Improvement on the Afterglow of Sr4Al14O25:Eu2+,Dy3+ Phosphor by Systematic Investigation on Various Parameters

    Directory of Open Access Journals (Sweden)

    Hom Nath Luitel

    2013-01-01

    Full Text Available Highly intense, long persistent Sr4Al14O25:Eu2+,Dy3+ blue-green phosphor with different B3+, Eu2+, Dy3+, and Ag+ contents was prepared by solid-phase reaction at various temperatures in reductive atmosphere of 10% H2 in N2. The effects of synthesis parameters like calcination temperature and time, calcination environment, effect of stoichiometry of the host composition, and additives like addition of boron and rare earth ions (Eu, Dy were studied in detail. Results revealed that the phosphor containing ~40 mol% H3BO3 showed dense and pure Sr4Al14O25 phase with higher emission intensity, but in the samples containing less than 20 mol% H3BO3 mixed phases consisting of Al2O3, SrAl12O19 and SrAl2O4 were observed, while in higher H3BO3 content, SrAl2B2O7 phases predominated. When the stoichiometry of Al/Sr was 3.7, the best phosphorescence and afterglow were noted. The phosphor containing 4 at.% of Eu and 8 at.% of Dy, and 3 at.% Ag exhibited the maximum initial intensity of 5170 mcd·m−2 and the longest persistency of greater than 30 hours over the value of 5 mcd·m−2, higher than the commercial products and applicable for various display applications involving indoor as well as outdoor uses.

  1. Ag/BiOBr Film in a Rotating-Disk Reactor Containing Long-Afterglow Phosphor for Round-the-Clock Photocatalysis.

    Science.gov (United States)

    Yin, Haibo; Chen, Xiaofang; Hou, Rujing; Zhu, Huijuan; Li, Shiqing; Huo, Yuning; Li, Hexing

    2015-09-16

    Ag/BiOBr film coated on the glass substrate was synthesized by a solvothermal method and a subsequent photoreduction process. Such a Ag/BiOBr film was then adhered to a hollow rotating disk filled with long-afterglow phosphor inside the chamber. The Ag/BiOBr film exhibited high photocatalytic activity for organic pollutant degradation owing to the improved visible-light harvesting and the separation of photoinduced charges. The long-afterglow phosphor could absorb the excessive daylight and emit light around 488 nm, activating the Ag/BiOBr film to realize round-the-clock photocatalysis. Because the Ag nanoparticles could extend the light absorbance of the Ag/BiOBr film to wavelengths of around 500 nm via a surface plasma resonance effect, they played a key role in realizing photocatalysis induced by long-afterglow phosphor.

  2. Multiple thermoluminescence glow peaks and afterglow suppression in CsI:Tl co-doped with Eu2+ or Yb2+

    Science.gov (United States)

    Bartram, R. H.; Kappers, L. A.; Hamilton, D. S.; Brecher, C.; Ovechkina, E. E.; Miller, S. R.; Nagarkar, V. V.

    2015-04-01

    CsI:Tl is a widely utilized scintillator material with many desirable properties but its applicability is limited by persistent afterglow. However, effective afterglow suppression has been achieved by co-doping with divalent lanthanides. The present report is concerned with observation of multiple thermoluminescence glow peaks in CsI:Tl,Eu and CsI:Tl,Yb, attributed to varying distributions of charge-compensating cation vacancies relative to divalent lanthanide co-dopants, and the subsequent modification of these distributions by repeated observations. It is observed that Yb2+ provides a slightly shallower electron trap than Eu2+, and that it can occupy a face-centered position by virtue of its relatively small ionic radius; the latter observation is confirmed by electrostatic calculations. It is also found that repeated observation of thermoluminescence in these materials has a modest adverse effect on afterglow suppression.

  3. Presymplectic structures and intrinsic Lagrangians

    CERN Document Server

    Grigoriev, Maxim

    2016-01-01

    It is well-known that a Lagrangian induces a compatible presymplectic form on the equation manifold (stationary surface, understood as a submanifold of the respective jet-space). Given an equation manifold and a compatible presymplectic form therein, we define the first-order Lagrangian system which is formulated in terms of the intrinsic geometry of the equation manifold. It has a structure of a presymplectic AKSZ sigma model for which the equation manifold, equipped with the presymplectic form and the horizontal differential, serves as the target space. For a wide class of systems (but not all) we show that if the presymplectic structure originates from a given Lagrangian, the proposed first-order Lagrangian is equivalent to the initial one and hence the Lagrangian per se can be entirely encoded in terms of the intrinsic geometry of its stationary surface. If the compatible presymplectic structure is generic, the proposed Lagrangian is only a partial one in the sense that its stationary surface contains the...

  4. Intrinsic Alignments in the Illustris Simulation

    CERN Document Server

    Hilbert, Stefan; Schneider, Peter; Springel, Volker; Vogelsberger, Mark; Hernquist, Lars

    2016-01-01

    We study intrinsic alignments (IA) of galaxy image shapes within the Illustris cosmic structure formation simulations. We investigate how IA correlations depend on observable galaxy properties such as stellar mass, apparent magnitude, redshift, and photometric type, and on the employed shape measurement method. The correlations considered include the matter density-intrinsic ellipticity (mI), galaxy density-intrinsic ellipticity (dI), gravitational shear-intrinsic ellipticity (GI), and intrinsic ellipticity-intrinsic ellipticity (II) correlations. We find stronger correlations for more massive and more luminous galaxies, as well as for earlier photometric types, in agreement with observations. Moreover, shape measurement methods that down-weight the outer parts of galaxy images produce much weaker IA signals on intermediate and large scales than methods employing flat radial weights. Thus, the expected contribution of intrinsic alignments to the observed ellipticity correlation in tomographic cosmic shear sur...

  5. Investigations into thermoluminescence and afterglow characterization of strontium aluminates with boron-modification and reductions via sol-gel route

    Institute of Scientific and Technical Information of China (English)

    Ⅰ-Cherng Chen; Ker-Kong Chen; Hong-Sen Chen; Je-kang Du; Tsao-Jen Lin; Shiu-Shiung Lin; Teng-Ming Chen; Tien-Yu Shieh

    2012-01-01

    The effects of strontium aluminates of SrAl2O4:Eu2+,Dy3+ (SAED) and boron-modified SAED (BSAED) phases synthesized from a sol-gel process on thermoluminescence (TL) along with their afterglow properties were systematically investigated with thermal activation in the different atmospheres.The result showed that the addition of boron and the reduction routes of Eu3+ to Eu2+ in SrAl2O4:Dy3+ were related to the phosphorescent decay properties.The aid of Dy3+ to induce the hole-trapping effect required both SAED and BSAED to be heated at 1300 ℃ under the H2/N2 (5%:95%) atmosphere.However,the trapping behavior of the reductions of SAED in nitrogen was similar to the compound without Dy3+ co-doping SrAl2O4:Eu2+ (SAE) in H2/N2 (5%:95%).BSAED showed deeper traps in situ compared to SAED which contained no boron,and this led to the better afterglow properties of BSAED than those of SAED.The afterglow spectrum of BSAED showed two peaks at 400+1 nm and 4854±1 nm,which were two individuals composed and contributed from different depths of traps at 0.57 and 0.76 eV,accordingly.The depth of the traps was calculated from the Hoogenstraaten's plot of glow curves.The calculations for SAED and SAE were at around 0.43 and 0.18 eV,respectively.

  6. DISCOVERY AND REDSHIFT OF AN OPTICAL AFTERGLOW IN 71 deg{sup 2}: iPTF13bxl AND GRB 130702A

    Energy Technology Data Exchange (ETDEWEB)

    Singer, Leo P.; Brown, Duncan A. [LIGO Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Bradley Cenko, S.; Gehrels, Neil; McEnery, Julie [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Kasliwal, Mansi M.; Mulchaey, John [Observatories of the Carnegie Institution for Science, 813 Santa Barbara St, Pasadena, CA 91101 (United States); Perley, Daniel A.; Kulkarni, S. R.; Bellm, Eric; Barlow, Tom; Cao, Yi; Horesh, Assaf [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Ofek, Eran O.; Arcavi, Iair [Benoziyo Center for Astrophysics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Nugent, Peter E.; Bloom, Joshua S. [Department of Astronomy, University of California Berkeley, B-20 Hearst Field Annex 3411, Berkeley, CA 94720-3411 (United States); Corsi, Alessandra [George Washington University, Corcoran Hall, Washington, DC 20052 (United States); Frail, Dale A. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Masci, Frank J., E-mail: lsinger@caltech.edu [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); and others

    2013-10-20

    We report the discovery of the optical afterglow of the γ-ray burst (GRB) 130702A, identified upon searching 71 deg{sup 2} surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization. Discovered and characterized by the intermediate Palomar Transient Factory, iPTF13bxl is the first afterglow discovered solely based on a GBM localization. Real-time image subtraction, machine learning, human vetting, and rapid response multi-wavelength follow-up enabled us to quickly narrow a list of 27,004 optical transient candidates to a single afterglow-like source. Detection of a new, fading X-ray source by Swift and a radio counterpart by CARMA and the Very Large Array confirmed the association between iPTF13bxl and GRB 130702A. Spectroscopy with the Magellan and Palomar 200 inch telescopes showed the afterglow to be at a redshift of z = 0.145, placing GRB 130702A among the lowest redshift GRBs detected to date. The prompt γ-ray energy release and afterglow luminosity are intermediate between typical cosmological GRBs and nearby sub-luminous events such as GRB 980425 and GRB 060218. The bright afterglow and emerging supernova offer an opportunity for extensive panchromatic follow-up. Our discovery of iPTF13bxl demonstrates the first observational proof-of-principle for ∼10 Fermi-iPTF localizations annually. Furthermore, it represents an important step toward overcoming the challenges inherent in uncovering faint optical counterparts to comparably localized gravitational wave events in the Advanced LIGO and Virgo era.

  7. The unusual optical afterglow of the gamma-ray burst GRB 021004 Color changes and short-time-scale variability

    CERN Document Server

    Bersier, D F; Winn, J N; Grav, T; Holman, M J; Matheson, T; Mochejska, B; Steeghs, D; Walker, A R; Garnavich, P M; Quinn, J; Jha, S; Calitz, H; Meintjes, P

    2003-01-01

    We report UBVRI observations of the optical afterglow of the gamma-ray burst GRB 021004. We observed significant (10-20%) deviations from a power law decay on several time scales, ranging from a few hours down to 20-30 minutes. We also observed a significant color change starting ~1.5 days after the burst, confirming the spectroscopic results already reported by Matheson et al. (2002). We discuss these results in the context of several models that have recently been proposed to account for the anomalous photometric behavior of this event.

  8. Afterglow, low-temperature radioluminescence and thermoluminescence of Lu{sub 2}O{sub 3}:Eu ceramic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Kappers, L.A. [Department of Physics, University of Connecticut, U-3046, 2152 Hiilside Road, Storrs, CT 06269-3046 (United States)]. E-mail: kappers@uconnvm.uconn.edu; Bartram, R.H. [Department of Physics, University of Connecticut, U-3046, 2152 Hiilside Road, Storrs, CT 06269-3046 (United States); Hamilton, D.S. [Department of Physics, University of Connecticut, U-3046, 2152 Hiilside Road, Storrs, CT 06269-3046 (United States); Brecher, C. [ALEM Associates, 303A Commonwealth Ave., Boston, MA 02115 (United States); Lempicki, A. [ALEM Associates, 303A Commonwealth Ave., Boston, MA 02115 (United States)

    2005-01-21

    Comparison of thermoluminescence (TL) and scintillation light outputs with continuous gamma-ray excitation reveals that the concentration of deep hole traps in ceramic Lu{sub 2}O{sub 3}:Eu, tentatively attributed to anion Frenkel defects, is enhanced by reversible radiation damage. Shallow electron and hole traps are tentatively attributed to surface states at grain boundaries. Electrons in shallow traps serve as non-radiative recombination centers. A model for anomalously persistent afterglow following pulsed X-ray excitation is based on a continuous distribution of hole traps inferred from TL following extended gamma-ray irradiation at -135 deg. C.

  9. Hole traps in Lu{sub 2}O{sub 3}:Eu ceramic scintillators. I. Persistent afterglow

    Energy Technology Data Exchange (ETDEWEB)

    Brecher, C.; Bartram, R.H. E-mail: rhbartram2@aol.com; Lempicki, A

    2004-03-01

    The temporal dependence of X-ray excited scintillation from Eu{sup 3+}-activated lutetium oxide transparent optical ceramic has been studied both experimentally and theoretically. The waveform of the decay was measured on time scales ranging from 100 ns to 5 min. Kinetic equations were applied and a computational model was developed to describe the observed temporal behavior. This model involves two overlapping Gaussian distributions of trap depths; those ranging from 0.58 to 1.0 eV may contribute to afterglow.

  10. Intrinsic optimization using stochastic nanomagnets

    Science.gov (United States)

    Sutton, Brian; Camsari, Kerem Yunus; Behin-Aein, Behtash; Datta, Supriyo

    2017-01-01

    This paper draws attention to a hardware system which can be engineered so that its intrinsic physics is described by the generalized Ising model and can encode the solution to many important NP-hard problems as its ground state. The basic constituents are stochastic nanomagnets which switch randomly between the ±1 Ising states and can be monitored continuously with standard electronics. Their mutual interactions can be short or long range, and their strengths can be reconfigured as needed to solve specific problems and to anneal the system at room temperature. The natural laws of statistical mechanics guide the network of stochastic nanomagnets at GHz speeds through the collective states with an emphasis on the low energy states that represent optimal solutions. As proof-of-concept, we present simulation results for standard NP-complete examples including a 16-city traveling salesman problem using experimentally benchmarked models for spin-transfer torque driven stochastic nanomagnets. PMID:28295053

  11. Intrinsic plasmarons in warm graphene

    Science.gov (United States)

    Liu, Daqing; Chen, Shuyue; Zhang, Shengli; Ma, Ning

    2017-10-01

    Based on a self-consistent method, we predict theoretically that there exist intrinsic plasmarons in graphene at nonzero temperature, with a well defined mode, as shown by the result of Landau damping. We find that there are sharp differences between the discussed system and the QCD/QED system. Firstly, the thermal mass is proportional to α_g3/4T but not αg T . Secondly, at 0c , the fermion channel and plasmaron channel are nearly degenerate, and furthermore the energy difference between fermion and plasmaron becomes larger and larger with increasing q in the region q>qc . Thirdly, the fermion behaves as a ‘relativistic particle’ with nonzero mass, and the plasmaron exhibits an abnormal dispersion at moderate momentum.

  12. Intrinsic Instability of Coronal Streamers

    CERN Document Server

    Chen, Y; Song, H Q; Shi, Q Q; Feng, S W; Xia, L D; 10.1088/0004-637X/691/2/1936

    2009-01-01

    Plasma blobs are observed to be weak density enhancements as radially stretched structures emerging from the cusps of quiescent coronal streamers. In this paper, it is suggested that the formation of blobs is a consequence of an intrinsic instability of coronal streamers occurring at a very localized region around the cusp. The evolutionary process of the instability, as revealed in our calculations, can be described as follows: (1) through the localized cusp region where the field is too weak to sustain the confinement, plasmas expand and stretch the closed field lines radially outward as a result of the freezing-in effect of plasma-magnetic field coupling; the expansion brings a strong velocity gradient into the slow wind regime providing the free energy necessary for the onset of a subsequent magnetohydrodynamic instability; (2) the instability manifests itself mainly as mixed streaming sausage-kink modes, the former results in pinches of elongated magnetic loops to provoke reconnections at one or many loc...

  13. Numerical simulations of dynamics and emission from relativistic astrophysical jets

    CERN Document Server

    Mimica, Petar; Rueda-Becerril, Jesus Misrayim; Tabik, Siham; Aloy, Carmen

    2012-01-01

    Broadband emission from relativistic outflows (jets) of active galactic nuclei (AGN) and gamma-ray bursts (GRBs) contains valuable information about the nature of the jet itself, and about the central engine which launches it. Using special relativistic hydrodynamics and magnetohydronamics simulations we study the dynamics of the jet and its interaction with the surrounding medium. The observational signature of the simulated jets is computed using a radiative transfer code developed specifically for the purpose of computing multi-wavelength, time-dependent, non-thermal emission from astrophysical plasmas. We present results of a series of long-term projects devoted to understanding the dynamics and emission of jets in parsec-scale AGN jets, blazars and the afterglow phase of the GRBs.

  14. Near-infrared-to-visible highly selective thermal emitters based on an intrinsic semiconductor.

    Science.gov (United States)

    Asano, Takashi; Suemitsu, Masahiro; Hashimoto, Kohei; De Zoysa, Menaka; Shibahara, Tatsuya; Tsutsumi, Tatsunori; Noda, Susumu

    2016-12-01

    Control of the thermal emission spectra of emitters will result in improved energy utilization efficiency in a broad range of fields, including lighting, energy harvesting, and sensing. In particular, it is challenging to realize a highly selective thermal emitter in the near-infrared-to-visible range, in which unwanted thermal emission spectral components at longer wavelengths are significantly suppressed, whereas strong emission in the near-infrared-to-visible range is retained. To achieve this, we propose an emitter based on interband transitions in a nanostructured intrinsic semiconductor. The electron thermal fluctuations are first limited to the higher-frequency side of the spectrum, above the semiconductor bandgap, and are then enhanced by the photonic resonance of the structure. Theoretical calculations indicate that optimized intrinsic Si rod-array emitters with a rod radius of 105 nm can convert 59% of the input power into emission of wavelengths shorter than 1100 nm at 1400 K. It is also theoretically indicated that emitters with a rod radius of 190 nm can convert 84% of the input power into emission of emissivity of 0.77 at a wavelength of 790 nm and a very low background emissivity of <0.02 to 0.05 at 1100 to 7000 nm, under operation at 1273 K. Use of a nanostructured intrinsic semiconductor that can withstand high temperatures is promising for the development of highly efficient thermal emitters operating in the near-infrared-to-visible range.

  15. Afterglow Observations of Fermi-LAT Gamma-Ray Bursts and the Emerging Class of Hyper-Energetic Events

    CERN Document Server

    Cenko, S B; Harrison, F A; Haislip, J B; Reichart, D E; Butler, N R; Cobb, B E; Cucchiara, A; Berger, E; Bloom, J S; Chandra, P; Fox, D B; Perley, D A; Prochaska, J X; Filippenko, A V; Glazebrook, K; Ivarsen, K M; Kasliwal, M M; Kulkarni, S R; LaCluyze, A P; Lopez, S; Morgan, A N; Pettini, M; Rana, V R

    2010-01-01

    We present broadband (radio, optical, and X-ray) light curves and spectra of the afterglows of four long-duration gamma-ray bursts (GRBs 090323, 090328, 090902B, and 090926A) detected by the Gamma-Ray Burst Monitor (GBM) and Large Area Telescope (LAT) instruments on the Fermi satellite. With its wide spectral bandpass, extending to GeV energies, Fermi is sensitive to GRBs with very large isotropic energy releases (10e54 erg). Although rare, these events are particularly important for testing GRB central-engine models. When combined with spectroscopic redshifts, our afterglow data for these four events are able to constrain jet collimation angles, the density structure of the circumburst medium, and both the true radiated energy release and the kinetic energy of the outflows. In agreement with our earlier work, we find that the relativistic energy budget of at least one of these events (GRB 090926A) exceeds the canonical value of 10e51 erg by an order of magnitude. Such energies pose a severe challenge for mod...

  16. Transition from interpulse to afterglow plasmas driven by repetitive short-pulse microwaves in a multicusp magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Shail; Sahu, Debaprasad; Bhattacharjee, Sudeep [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India)

    2012-08-15

    In the power-off phase, plasmas generated by repetitive short-pulse microwaves in a multicusp magnetic field show a transitive nature from interpulse to afterglow as a function of pulse duration t{sub w} = 20-200 {mu}s. The ionized medium can be driven from a highly non equilibrium to an equilibrium state inside the pulses, thereby dictating the behavior of the plasma in the power-off phase. Compared to afterglows, interpulse plasmas observed for t{sub w} < 50 {mu}s are characterized by a quasi-steady-state in electron density that persists for {approx} 20-40 {mu}s even after the end of the pulse and has a relatively slower decay rate ({approx} 4.3 Multiplication-Sign 10{sup 4} s{sup -1}) of the electron temperature, as corroborated by optical measurements. The associated electron energy probability function indicates depletion in low energy electrons which appear at higher energies just after the end of the pulse. The transition occurs at t{sub w} {approx} 50 {mu}s as confirmed by time evolution of integrated electron numbers densities obtained from the distribution function.

  17. Transition from interpulse to afterglow plasmas driven by repetitive short-pulse microwaves in a multicusp magnetic field

    Science.gov (United States)

    Pandey, Shail; Sahu, Debaprasad; Bhattacharjee, Sudeep

    2012-08-01

    In the power-off phase, plasmas generated by repetitive short-pulse microwaves in a multicusp magnetic field show a transitive nature from interpulse to afterglow as a function of pulse duration tw = 20-200 μs. The ionized medium can be driven from a highly non equilibrium to an equilibrium state inside the pulses, thereby dictating the behavior of the plasma in the power-off phase. Compared to afterglows, interpulse plasmas observed for tw < 50 μs are characterized by a quasi-steady-state in electron density that persists for ˜ 20-40 μs even after the end of the pulse and has a relatively slower decay rate (˜ 4.3 × 104 s-1) of the electron temperature, as corroborated by optical measurements. The associated electron energy probability function indicates depletion in low energy electrons which appear at higher energies just after the end of the pulse. The transition occurs at tw ˜ 50 μs as confirmed by time evolution of integrated electron numbers densities obtained from the distribution function.

  18. The Influence of Temperature on the Afterglow Feature of SrAl2O4∶Eu,Dy Phosphors

    Institute of Scientific and Technical Information of China (English)

    WANG Bing; ZHUO Zhiyun; LU Zhongyuan

    2006-01-01

    Using a self-designed temperature testing box in which Xenon-lamp irradiation can be applied, the afterglow feature of SrAl2O4:Eu,Dy as a function of temperature has been researched. Two sorts of SrAl2O4:Eu,Dy phosphors, namely highest quality commercial one and the self-synthesized one by solid-state reaction process were employed. Results reveal a common phenomenon behaving as phosphorescent sudden extinguishments at a certain low temperature although their threshold temperature value (about 223 K) has a slight difference. The general characteristic for the influence of temperature on the afterglow feature presents, compared to the luminescent decay at room temperature (RT), a bigger and faster decrease of phosphorescent brightness with the reduction of temperature, while decay curves still maitain the same pattern composed of a quick decline part and a platform falling part during which the phosphorescent brightness at 273 K is only about 1/2 as big as that at RT, and at 253 K the figure has changed to about 1/3. Finally, the reason of previous observed results has been analyzed briefly in theory.

  19. Helium in natal HII regions: the origin of the X-ray absorption in gamma-ray burst afterglows

    CERN Document Server

    Watson, Darach; Andersen, Anja C; Fynbo, Johan P U; Gorosabel, Javier; Hjorth, Jens; Jakobsson, Páll; Krühler, Thomas; Laursen, Peter; Leloudas, Giorgos; Malesani, Daniele

    2012-01-01

    Soft X-ray absorption in excess of Galactic is observed in the afterglows of most gamma-ray bursts (GRBs), but the correct solution to its origin has not been arrived at after more than a decade of work, preventing its use as a powerful diagnostic tool. We resolve this long-standing problem and find that He in the GRB's host HII region is responsible for most of the absorption. We show that the X-ray absorbing column density (N_Hx) is correlated with both the neutral gas column density and with the optical afterglow extinction (Av). This correlation explains the connection between dark bursts and bursts with high N_Hx values. From these correlations we exclude an origin of the X-ray absorption which is not related to the host galaxy, i.e. the intergalactic medium or intervening absorbers are not responsible. We find that the correlation with the dust column has a strong redshift evolution, whereas the correlation with the neutral gas does not. From this we conclude that the column density of the X-ray absorpt...

  20. Off-axis emission of short gamma-ray bursts and the detectability of electromagnetic counterparts of gravitational wave detected binary mergers

    CERN Document Server

    Lazzati, Davide; Morsony, Brian J; Workman, Jared C

    2016-01-01

    We present calculations of the wide angle emission of short-duration gamma-ray bursts from compact binary merger progenitors. Such events are expected to be localized by their gravitational wave emission, fairly irrespective of the orientation of the angular momentum vector of the system, along which the gamma-ray burst outflow is expected to propagate. We show that both the prompt and afterglow emission are dim and challenging to detect for observers lying outside of the cone within which the relativistic outflow is propagating. If the jet initially propagates through a baryon contaminated region surrounding the merger site, however, a hot cocoon forms around it. The cocoon subsequently expands quasi-isotropically producing its own prompt emission and external shock powered afterglow. We show that the cocoon afterglow peaks a few hours to a few days after the burst and is detectable for up to a few weeks at all wavelengths. For a significant fraction of the gravitationally-detected neutron-star-binary merger...

  1. Design of intrinsically safe power supply

    Institute of Scientific and Technical Information of China (English)

    LI Rui-jin; JIN Lin

    2012-01-01

    Aiming to make a high power direct current supply safely used in coal mine production,this paper made a deep research on characteristics of intrinsically safe power supply,using the mathematical model established according to coal mine intrinsic safety standards.It provides theory support for the application of high power intrinsically safe power supply.The released energy of output short circuit of switch power supply,and the close related factors that influence the biggest output short-circuit spark discharge energy are the theoretical basis of the power supply.It is shown how to make a high power intrinsically safe power supply using the calculated values in the mathematical model,and take values from intrinsically safe requirements parameters scope,then this theoretical calculation value can be developed as the ultimate basis for research of the power supply.It gets the identification method of intrinsically safe from mathematics model of intrinsically safe power supply characteristics study,which solves the problem of theory and application of designing different power intrinsically safe power supply,and designs a kind of high power intrinsically safe power supply through this method.

  2. Algebraic description of intrinsic modes in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A. (Los Alamos National Lab., NM (USA))

    1990-01-01

    We present a procedure for extracting normal modes in algebraic number-conserving systems of interacting bosons relevant for collective states in even-even nuclei. The Hamiltonian is resolved into intrinsic (bandhead related) and collective (in-band related) parts. Shape parameters are introduced through non-spherical boson bases. Intrinsic modes decoupled from the spurious modes are obtained from the intrinsic part of the Hamiltonian in the limit of large number of bosons. Intrinsic states are constructed and serve to evaluate electromagnetic transition rates. The method is illustrated for systems with one type of boson as well as with proton-neutron bosons. (author).

  3. Incentives and intrinsic motivation in healthcare

    Directory of Open Access Journals (Sweden)

    Mikel Berdud

    2016-11-01

    Conclusions: The conclusions could act as a guide to support the optimal design of incentive policies and schemes within health organisations when healthcare professionals are intrinsically motivated.

  4. Growth and characterization of group iiinitrides by migration-enhanced afterglow epitaxy

    Science.gov (United States)

    Gergova, Rositsa

    The work presented in this thesis investigates the growth and properties of group III- nitride semiconductors that were grown using the Migration Enhanced Afterglow Epitaxy (MEAglow) method. This work was to enhance the understanding of the MEAglow growth process towards the improvement of quality of the layers grown using this technique. The MEAglow technique applies the migration enhanced epitaxy method in a low pressure plasma-based CVD reactor, which has a potential of producing high quality epitaxial group III-nitride layers at relatively low growth temperatures on large deposition areas. The low temperature pulse growth in metal-rich regime, comprising the MME method was employed under growth pressures between 500 mTorr and 3000 mTorr. As the MME method up to this point has been used only for MBE systems, study of the impact of the growth pressure on the materials properties was necessary. In this work the pressure dependence was mapped to an existing surface phase diagram for MBE systems by calculating the number of nitrogen gas phase collisions and the metalorganic bombardment rate, for the specific to the prototype reactor parameters, to a first approximation. This was done in order to achieve an intermediate regime free of metal droplets for growth in metal-rich regime. High quality epitaxial InN layers were accomplished on extremely thin and smooth Ga2O3 buffer layers. These results indicate a potential for the application of Ga2O3 buffers in InN growth. The MEAglow InN layers were further optimized for growth on commercially available GaN buffer layers and excellent two-dimensional growth was achieved for layers grown under metal-rich conditions at 512 °C. Post-growth annealing studies were carried out for InN layers grown at temperatures below 400 °C to study the limiting processes of the removal of excess nitrogen, believed to be a dominant defect in InN films grown in plasma-based systems at very low temperatures. Variations in GaN stoichiometry

  5. THE NEEDLE IN THE 100 deg{sup 2} HAYSTACK: UNCOVERING AFTERGLOWS OF FERMI GRBs WITH THE PALOMAR TRANSIENT FACTORY

    Energy Technology Data Exchange (ETDEWEB)

    Singer, Leo P. [LIGO Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Kasliwal, Mansi M. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena CA 91101 (United States); Cenko, S. Bradley; Cucchiara, Antonino; Gehrels, Neil [Astrophysics Science Division, NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771 (United States); Perley, Daniel A.; Cao, Yi [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Anderson, Gemma E.; Fender, Rob P. [Astrophysics, Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Anupama, G. C. [Indian Institute of Astrophysics, Koramangala, Bangalore 560 034 (India); Arcavi, Iair [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Bhalerao, Varun [Inter-University Centre for Astronomy and Astrophysics (IUCAA), Post Bag 4, Ganeshkhind, Pune 411007 (India); Bue, Brian D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Connaughton, Valerie [CSPAR and Physics Department, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States); Corsi, Alessandra [Texas Tech University, Physics Department, Lubbock, TX 79409-1051 (United States); Fox, Derek B. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Goldstein, Adam [Astrophysics Office, ZP12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Gorosabel, J. [Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, E-18008, Granada (Spain); Horesh, Assaf, E-mail: leo.p.singer@nasa.gov [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel); and others

    2015-06-10

    The Fermi Gamma-ray Space Telescope has greatly expanded the number and energy window of observations of gamma-ray bursts (GRBs). However, the coarse localizations of tens to a hundred square degrees provided by the Fermi GRB Monitor instrument have posed a formidable obstacle to locating the bursts’ host galaxies, measuring their redshifts, and tracking their panchromatic afterglows. We have built a target-of-opportunity mode for the intermediate Palomar Transient Factory in order to perform targeted searches for Fermi afterglows. Here, we present the results of one year of this program: 8 afterglow discoveries out of 35 searches. Two of the bursts with detected afterglows (GRBs 130702A and 140606B) were at low redshift (z = 0.145 and 0.384, respectively) and had spectroscopically confirmed broad-line Type Ic supernovae. We present our broadband follow-up including spectroscopy as well as X-ray, UV, optical, millimeter, and radio observations. We study possible selection effects in the context of the total Fermi and Swift GRB samples. We identify one new outlier on the Amati relation. We find that two bursts are consistent with a mildly relativistic shock breaking out from the progenitor star rather than the ultra-relativistic internal shock mechanism that powers standard cosmological bursts. Finally, in the context of the Zwicky Transient Facility, we discuss how we will continue to expand this effort to find optical counterparts of binary neutron star mergers that may soon be detected by Advanced LIGO and Virgo.

  6. Intrinsically photosensitive retinal ganglion cells

    Institute of Scientific and Technical Information of China (English)

    Gary; E.PICKARD; Patricia; J.SOLLARS

    2010-01-01

    A new mammalian photoreceptor was recently discovered to reside in the ganglion cell layer of the inner retina.These intrinsically photosensitive retinal ganglion cells(ipRGCs) express a photopigment,melanopsin,that confers upon them the ability to respond to light in the absence of all rod and cone photoreceptor input.Although relatively few in number,ipRGCs extend their dendrites across large expanses of the retina making them ideally suited to function as irradiance detectors to assess changes in ambient light levels.Phototransduction in ipRGCs appears to be mediated by transient receptor potential channels more closely resembling the phototransduction cascade of invertebrate rather than vertebrate photoreceptors.ipRGCs convey irradiance information centrally via the optic nerve to influence several functions.ipRGCs are the primary retinal input to the hypothalamic suprachiasmatic nucleus(SCN),a circadian oscillator and biological clock,and this input entrains the SCN to the day/night cycle.ipRGCs contribute irradiance signals that regulate pupil size and they also provide signals that interface with the autonomic nervous system to regulate rhythmic gene activity in major organs of the body.ipRGCs also provide excitatory drive to dopaminergic amacrine cells in the retina,providing a novel basis for the restructuring of retinal circuits by light.Here we review the ground-breaking discoveries,current progress and directions for future investigation.

  7. Tuning the afterglow plasma composition in Ar/N2/O2 mixtures: characteristics of a flowing surface-wave microwave discharge system

    Science.gov (United States)

    Kutasi, Kinga; Noël, Cédric; Belmonte, Thierry; Guerra, Vasco

    2016-10-01

    A self-consistent kinetic model is used to study the possibility of tuning the plasma composition in the afterglow of a flowing surface-wave microwave discharge by the different discharge and system parameters in the case of 90%Ar-10%(N2-O2) and N2-O2 mixtures. The afterglow system consists of a 0.5 cm diameter quartz tube of 50 cm in length—where the discharge is generated and the early-afterglow develops—and an afterglow reactor. The plasma composition is studied at the end of the discharge plasma column and at the reactor inlet as a function of the N2:O2 ratio for selected conditions, which are set with the system parameters and are illustrated in the experimental set-up. The validity of the model used is proven by the agreement of the calculated atomic densities with those measured by mass spectrometry. Due to the pressure drop along the tube, the position of the discharge (which also defines the lengths of the early-afterglow, t aft) and the discharge pressure (p dis) can be set with the position of the wave coupler—surfatron—along the tube at a constant gas flow rate (which defines the pressure in the reactor, p reac). It is shown that the relative densities of species at the end of plasma column, which constitute the initial condition for the afterglow, depend on the discharge pressure. Therefore, at a constant gas flow rate with the position of the surfatron the plasma composition in the reactor is changing due to the variation of both the p dis and t aft. The evolution of the plasma composition is also studied when both the surfatron’s position and the gas flow rate are changed, realizing conditions (i) with the same p dis, and different t aft and p reac, and (ii) with the same t aft, and different p dis and p reac. Comparing the N2-O2 binary and the ternary mixtures, it is shown that the atomic densities obtained in the binary mixtures can be reproduced in ternary mixtures with different N2:O2 ratios. Furthermore, according to the spectra

  8. Rotational Crofton formulae for flagged intrinsic volumes

    DEFF Research Database (Denmark)

    Auneau, Jeremy Michel

    , and the integration is over all sections containing the fixed point origo. Our main result is a local stereological analogue to the well-known Crofton formula. More precisely, we derive geometric formulae that relate new flagged intrinsic volumes of a set with the flagged intrinsic volumes of its sections...

  9. Intrinsic bioremediation of landfills interim report

    Energy Technology Data Exchange (ETDEWEB)

    Brigmon, R.L. [Westinghouse Savannah River Company, Aiken, SC (United States); Fliermans, C.B.

    1997-07-14

    Intrinsic bioremediation is a risk management option that relies on natural biological and physical processes to contain the spread of contamination from a source. Evidence is presented in this report that intrinsic bioremediation is occurring at the Sanitary Landfill is fundamental to support incorportion into a Corrective Action Plan (CAP).

  10. Luminescence and red long afterglow investigation of Eu{sup 3{sup +}}-Sm{sup 3{sup +}} CO-doped CaWO{sub 4} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Kang Fengwen [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, WaiHuan Xi Road, No.100, Guangzhou 510006 (China); Hu Yihua, E-mail: huyh@gdut.edu.cn [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, WaiHuan Xi Road, No.100, Guangzhou 510006 (China); Wu Haoyi; Mu Zhongfei; Ju Guifang; Fu Chujun; Li Nana [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, WaiHuan Xi Road, No.100, Guangzhou 510006 (China)

    2012-04-15

    A series of Eu{sup 3+}-Sm{sup 3+} co-doped CaWO{sub 4} phosphors were synthesized by the high temperature solid-state method. The crystal structure of the obtained samples was identified by XRD, and the results showed that all the phases were indexed to scheelite structure. The effect of the doping concentration of Sm{sup 3+} on the luminescent properties of the obtained products was investigated, and the optimal Sm{sup 3+} concentration was experimentally determined to 0.5%. The photoluminescence properties indicate that there is an efficient energy transfers from Sm{sup 3+} to Eu{sup 3+}. The energy-transfer process between Sm{sup 3+} and Eu{sup 3+} was also given. Red long afterglow originating from the {sup 5}D{sub 0}-{sup 7}F{sub J} (J=0, 1, 2, 3, 4) transitions of Eu{sup 3+} was observed after samples were excited by 254 nm, and the duration of the optimal sample can last more than 35 min in dark with naked eyes. The proposed explanation for the afterglow property was also discussed. - Highlights: Black-Right-Pointing-Pointer The afterglow of Eu{sup 3{sup +}} and its enhancement by Sm{sup 3{sup +}} co-doping in CaWO{sub 4} is studied. Black-Right-Pointing-Pointer An optimal Sm{sup 3{sup +}} doping concentration for the Eu{sup 3{sup +}} afterglow properties was found. Black-Right-Pointing-Pointer The mechanism of energy transfer between Sm{sup 3{sup +}} and Eu{sup 3{sup +}} is presented, and the proposed cause of long afterglow was discussed.

  11. Swift and Fermi observations of the early afterglow of the short Gamma-Ray Burst 090510

    CERN Document Server

    De Pasquale, M; Kuin, N P M; Page, M J; Curran, P A; Zane, S; Oates, S R; Holland, S T; Breeveld, A A; Hoversten, E A; Chincarini, G; Grupe, D

    2009-01-01

    We present the observations of GRB090510 performed by the Fermi Gamma-Ray Space Telescope and the Swift observatory. This is a bright, short burst that shows an extended emission detected in the GeV range. Furthermore, its optical emission initially rises, a feature so far observed only in long bursts, while the X-ray flux shows an initial shallow decrease, followed by a steeper decay. This exceptional behavior enables us to investigate the physical properties of the GRB outflow, poorly known in short bursts. We discuss internal shock and external shock models for the broadband energy emission of this object.

  12. Flowing afterglow: construction of an apparatus, measurement of rate constants, and consideration of the diffusive behavior of charges

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, Shingo; Nakamura, Hirone; Tamura, Takaaki (Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.); Fujii, Toshihiro

    1984-06-01

    A flowing afterglow apparatus was constructed and the operation of the afterglow system including data analysis was tested by measuring the rate constants for the reactions N/sup +/ + NO, N/sub 2//sup +/ + NO, He/sup +/ + N/sub 2/, and SF/sub 6/ + e; the results were 5.8 x 10/sup -10/, 3.9 x 10/sup -10/, 1.20 x 10/sup -9/, and 2.1 x 10/sup -7/ cm/sup 3/s/sup -1/ respectively. In the measurements an extraction voltage for ion sampling was not applied to the nose cone in order not to introduce an electric field into the reaction region. A ''non-ambipolar'' model developed by us was used for the data analysis of the ion/molecule reactions. For the data analysis of the electron attachment, a typical curve fit mehtod to the product ion signal was used. However, no theoretical curves fit the experimental points. This disagreement is attributed to a change of the ion-sampling efficiency through the nose-cone aperture arising from a change of the electron-dominated plasma to a negative-ion-dominated plasma with an increasing flow rate of SF/sub 6/. Nevertheless, the attachment rate could be determined by fitting the theoretical and experimantal curves in the limited region of the SF/sub 6/ flow rate where the negative-ion-dominated plasma is established at the sampling aperture. All the rate constants obtained here agree reasonably well with literature values. Next, errors in the positive ion/molecule reaction rate constants, which would occur if the diffusion coefficients of the ions and neutrals each have a + 10 % error were calculated for the flow model to be -0.4 and +1.2 % respectively, demonstrating that these parameters are not important in the analysis of data. This insensitivity explains why the nose-cone voltage applied in a typical flowing afterglow operation has not caused a significant error in the published rate constants although it disturbs the ion diffusive behavior.

  13. Intrinsic structure in Saturn's rings

    Science.gov (United States)

    Albers, N.

    2015-10-01

    Saturn's rings are the most prominent in our Solar system and one example of granular matter in space. Dominated by tides and inelastic collisions the system is highly flattened being almost 300000km wide while only tens of meters thick. Individual particles are composed of primarily water ice and range from microns to few tens of meters in size. Apparent patterns comprise ringlets, gaps, kinematic wakes, propellers, bending waves, and the winding spiral arms of density waves. These large-scale structures are perturbations foremost created by external as well as embedded moons. Observations made by the Cassini spacecraft currently in orbit around Saturn show these structures in unprecedented detail. But high-resolution measurements reveal the presence of small-scale structures throughout the system. These include self-gravity wakes (50-100m), overstable waves (100-300m), subkm structure at the A and B ring edges, "straw" and "ropy" structures (1-3km), and the C ring "ghosts". Most of these had not been anticipated and are found in perturbed regions, driven by resonances with external moons, where the system undergoes periodic phases of compression and relaxation that correlate with the presence of structure. High velocity dispersion and the presence of large clumps imply structure formation on time scales as short as one orbit (about 10 hours). The presence of these intrinsic structures is seemingly the response to varying local conditions such as internal density, optical depth, underlying particle size distribution, granular temperature, and distance from the central planet. Their abundance provides evidence for an active and dynamic ring system where aggregation and fragmentation are ongoing on orbital timescales. Thus a kinetic description of the rings may be more appropriate than the fluid one. I will present Cassini Ultraviolet Spectrometer (UVIS) High Speed Photometer (HSP) occultations, Voyager 1 and 2 Imaging Science Subsystem (ISS), and high

  14. Non-equilibrium vibrational and electron energy distribution functions in mtorr, high-electron-density nitrogen discharges and afterglows

    Science.gov (United States)

    Capitelli, M.; Colonna, G.; D’Ammando, G.; Laricchiuta, A.; Pietanza, L. D.

    2017-03-01

    Non-equilibrium vibrational distributions (vdf) and non-equilibrium electron energy distribution functions (eedf) in a nitrogen plasma at low pressure (mtorr) have been calculated by using a time-dependent plasma physics model coupled to the Boltzmann equation and heavy particle kinetics. Different case studies have been selected showing the non-equilibrium character of both vdf and eedf under discharge and post-discharge conditions in the presence of large concentrations of electrons. Particular attention is devoted to the electron-molecule resonant vibrational excitation cross sections acting in the whole vibrational ladder. The results in the post-discharge conditions show the interplay of superelastic vibrational and electronic collisions in forming structures in the eedf. The link between the present results in the mtorr afterglow regime with the existing eedf in the torr and atmospheric regimes is discussed.

  15. Inactivation of Candida glabrata by a humid DC argon discharge afterglow: dominant contributions of short-lived aqueous active species

    Science.gov (United States)

    Xiong, Qing; Liu, Hongbin; Lu, Weiping; Chen, Qiang; Xu, Le; Wang, Xia; Zhu, Qunlin; Zeng, Xue; Yi, Ping

    2017-05-01

    Plasma medicine applications are currently attracting significant interest all over the world. Bactericidal treatments of Candida glabrata cultured in saline suspension are performed in this study by a room-temperature reactive afterglow of a DC-driven argon discharge. Water vapor was added to the discharge to study the inactivation contributions of reactive hydrolytic species including OH and H2O2 transporting along the gas flow to the treated solutions. The inactivation results indicate that the dominant roles in the bactericidal treatments are played by the short-lived aqueous active species, but not the stable species like H2O2aq (aq indicates an aqueous species). Further analysis shows that the ·OHaq radicals play an important role in the inactivation process. The ·OHaq radicals in the suspension are mostly produced from the direct dissolution of the OH species in the reactive afterglow. With the increase of added water vapor content, the ·OHaq production increases and enhances the inactivation efficiency of C. glabrata. Furthermore, it is found that the ambient air diffusion shows essential effects on the bactericidal activity of the remote humid argon discharge. Higher bactericidal effects can be obtained in open-space treatments compared to in a controlled Ar + H2O gas atmosphere. Key active air-byproduct species are believed to be generated in the suspension during the treatments and contributing to the inactivation process. Based on chemical analysis, the peroxynitrous acid ONOOHaq is considered as the key antimicrobial air-byproduct species. These results indicate the important dependence of plasma biomedical effects on the processing environment, which finally relates to the critical contributions of the key reactive species formed therein.

  16. Algebraic description of intrinsic modes in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Leviatan, A.

    1989-01-01

    We present a procedure for extracting normal modes in algebraic number-conserving systems of interacting bosons relevant for collective states in even-even nuclei. The Hamiltonian is resolved into intrinsic (bandhead related) and collective (in-band related) parts. Shape parameters are introduced through non-spherical boson bases. Intrinsic modes decoupled from the spurious modes are obtained from the intinsic part of the Hamiltonian in the limit of large number of bosons. Intrinsic states are constructed and serve to evaluate electromagnetic transition rates. The method is illustrated for systems with one type of boson as well as with proton-neutron bosons. 28 refs., 1 fig.

  17. GRB 080503: Implications of a Naked Short Gamma-Ray Burst Dominated by Extended Emission

    CERN Document Server

    Perley, D A; Granot, J; Butler, N R; Sakamoto, T; Ramirez-Ruiz, E; Levan, A J; Bloom, J S; Miller, A A; Bunker, A; Chen, H -W; Filippenko, A V; Gehrels, N; Glazebrook, K; Hall, P; Hurley, K C; Kocevski, D; Li, W; López, S; Norris, J; Piro, A L; Poznanski, D; Prochaska, J X; Quataert, E; Tanvir, N

    2008-01-01

    We report on observations of GRB 080503, a short gamma-ray burst with very bright extended emission (about 30 times the gamma-ray fluence of the initial spike) in conjunction with a thorough comparison to other short Swift events. In spite of the prompt-emission brightness, however, the optical counterpart is extraordinarily faint, never exceeding 25 mag in deep observations starting at ~1 hr after the BAT trigger. The optical brightness peaks at ~1 day and then falls sharply in a manner similar to the predictions of Li & Paczynski (1998) for supernova-like emission following compact-binary mergers. However, a shallow spectral index and similar evolution in X-rays inferred from Chandra observations are more consistent with an afterglow interpretation. The extreme faintness of this probable afterglow relative to the bright gamma-ray emission argues for a very low-density medium surrounding the burst (a "naked" GRB), consistent with the lack of a coincident host galaxy down to 28.5 mag in deep HST imaging. ...

  18. Scattered emission from a relativistic outflow and its application to gamma-ray bursts

    Science.gov (United States)

    Shen, R.-F.; Barniol Duran, R.; Kumar, P.

    2008-03-01

    We investigate a scenario of photon scattering by electrons within a relativistic outflow. The outflow is composed of discrete shells with different speeds. One shell emits radiation for a short duration. Some of this radiation is scattered by the shell(s) behind. We calculate in a simple two-shell model the observed scattered flux density as a function of the observed primary flux density, the normalized arrival time delay between the two emission components, the Lorentz factor ratio of the two shells and the scattering shell's optical depth. Thomson scattering in a cold shell and inverse Compton scattering in a hot shell are both considered. The results of our calculations are applied to the gamma-ray bursts and the afterglows. We find that the scattered flux from a cold slower shell is small and likely to be detected only for those bursts with very weak afterglows. A hot scattering shell could give rise to a scattered emission as bright as the X-ray shallow decay component detected in many bursts, on a condition that the isotropically equivalent total energy carried by the hot electrons is large, ~1052-1056 erg. The scattered emission from a faster shell could appear as a late short γ-ray/MeV flash or become part of the prompt emission depending on the delay of the ejection of the shell.

  19. The Supercritical Pile Model: Prompt Emission Across the Electromagnetic Spectrum

    Science.gov (United States)

    Kazanas, Demos; Mastichiadis, A.

    2008-01-01

    The "Supercritical Pile" GRB model is an economical model that provides the dissipation necessary to convert explosively the energy stored in relativistic protons in the blast wave of a GRB into radiation; at the same time it produces spectra whose luminosity peaks at 1 MeV in the lab frame, the result of the kinematics of the proton-photon - pair production reaction that effects the conversion of proton energy to radiation. We outline the fundamental notions behind the "Supercritical Pile" model and discuss the resulting spectra of the prompt emission from optical to gamma-ray energies of order Gamma^2 m_ec^2, (Gamma is the Lorentz factor of the blast wave) present even in the absence of an accelerated particle distribution and compare our results to bursts that cover this entire energy range. Particular emphasis is given on the emission at the GLAST energy range both in the prompt and the afterglow stages of the burst.

  20. The Supercritical Pile Model: Prompt Emission Across the Electromagnetic Spectrum

    Science.gov (United States)

    Kazanas, Demos; Mastichiadis, A.

    2008-01-01

    The "Supercritical Pile" GRB model is an economical model that provides the dissipation necessary to convert explosively the energy stored in relativistic protons in the blast wave of a GRB into radiation; at the same time it produces spectra whose luminosity peaks at 1 MeV in the lab frame, the result of the kinematics of the proton-photon - pair production reaction that effects the conversion of proton energy to radiation. We outline the fundamental notions behind the "Supercritical Pile" model and discuss the resulting spectra of the prompt emission from optical to gamma-ray energies of order Gamma^2 m_ec^2, (Gamma is the Lorentz factor of the blast wave) present even in the absence of an accelerated particle distribution and compare our results to bursts that cover this entire energy range. Particular emphasis is given on the emission at the GLAST energy range both in the prompt and the afterglow stages of the burst.